CLA reduces weight, blood sugar and leptin levels

Supplementing the diet with a certain fatty acid may lead to better weight control and disease management in diabetics, a new study suggests.Diabetics who added an essential fatty acid called conjugated linoleic acid (CLA) to their diets had lower body mass as well as lower blood sugar levels by the end of the eight-week study. Hyperglycemia, or high blood sugar, is a hallmark of diabetes.

Researchers also found that higher levels of this fatty acid in the bloodstream meant lower levels of leptin, a hormone thought to regulate fat levels. Scientists think that high leptin levels may play a role in obesity, one of the biggest risk factors for adult-onset diabetes.

“In previous work, we found that CLA delayed the onset of diabetes in rats,” said Martha Belury, the senior author of the study and an associate professor of human nutrition at Ohio State University. “In this study, we found that it also helped improve the management of adult-onset diabetes in humans.”

CLA is made up of various fatty acid isomers – compounds that share the same chemical formula but differ in chemical structure. Related isomers can have very different effects.

In the current study, the researchers found that one particular CLA isomer, t10c12-CLA, helped control both body weight and leptin levels. Nutritionists sometimes call this isomer the 10-12, isomer.

The research appears in the January issue of the Journal of Nutrition. Belury conducted the study while with the department of foods and nutrition at Purdue University. She is continuing the research at Ohio State.

The researchers asked 21 people with adult-onset diabetes to take either a supplement containing a mix of rumenic acid and 10-12 isomer or a safflower oil supplement as a control. The group was divided roughly in half. Rumenic acid is the predominant isomer in foods that contain CLA, while the 10-12 isomer is less abundant.

Participants were instructed to take their respective supplements every day for eight weeks.

“The amount of CLA, how long it’s taken and the type taken all impact the fatty acid’s ability to affect obesity in humans, and therefore help manage diabetes.”

While CLA supplements are available to consumers, Belury encourages diabetics to get their CLA from food sources – primarily beef, lamb and dairy products.

“Not only does it taste better, it’s also safer and more beneficial to get the nutrients from food,” she said. “Besides, we don’t yet know the long-term effects of taking CLA in supplement form.”

At the end of the trial, the researchers took blood samples from each participant to check CLA levels. By then, fasting blood glucose levels had decreased in nine of the 11 people taking the CLA supplement, but only in two of the 10 taking safflower supplements, meaning that CLA was helping to control certain symptoms of diabetes.

Fasting blood glucose levels decreased nearly five-fold in patients taking CLA, compared to patients taking the safflower oil.

The researchers also studied the impact each isomer had on changes in body weight and levels of the hormone leptin.

It was the 10-12 isomer, and not rumenic acid, that was linked to a reduction in body weight and leptin levels. While the average weight loss among patients taking CLA supplements was small (about 3.5 pounds), they had been asked to not change their normal caloric intake during the study. The group taking safflower supplements neither lost nor gained weight. Leptin levels decreased in the CLA group, and rose slightly in the safflower group.

“The effect of the 10-12 isomer on reducing body mass and leptin levels was key,” Belury said, adding that other researchers have shown the 10-12 isomer to be helpful in reducing body mass in animals.

“The amount of CLA, how long it’s taken and the type taken all impact the fatty acid’s ability to affect obesity in humans, and therefore help manage diabetes,” Belury said.

A 2002 study conducted by the Diabetes Prevention Program Research Group found that a modest reduction in body weight resulted in a 58 percent reduction in the incidence of diabetes in a group of people at high risk for developing the disease.

Belury conducted the study with Annie Mahon of the department of foods and nutrition at Purdue University and Sebastiano Banni of the department of experimental biology at the University of Cagliari, Italy.

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Article adapted by MD Only Weblog from original press release.
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Contact: Martha A. Belury
Ohio State University

Low testosterone levels associated with depression in men

Men with low testosterone levels are more likely to be depressed, according to an article in the February issue of The Archives of General Psychiatry, one of the JAMA/Archives journals.According to information in the article, testosterone deficiency (hypogonadism) is a common condition in older men, occurring in 30 percent of men older than 55. Testosterone levels peak in early adulthood, and then decrease by approximately 1 percent per year after age 40. Symptoms of hypogonadism include decreased muscle mass and strength, decreased bone mineral density, diminished appetite, decreased libido, fatigue and irritability. Some symptoms overlap with those of depression, but the association between hypogonadism and depression is unclear.

Molly M. Shores, M.D., of Veterans Affairs Puget Sound Health Care System, Seattle, and colleagues examined the clinical records of 278 men (45 years or older) without depression to examine the relationship between testosterone level and the incidence of diagnosed depression over a two-year period.

The researchers found that over the study period, 21.7 percent of the hypogonadal men were diagnosed with depression, vs. 7.1 percent of men with normal testosterone levels. When the researchers adjusted for age, alcohol use disorders, prostate cancer, and other medical conditions, they found that men with hypogonadism were 4.2 times more likely to be diagnosed with depression. “Hypogonadal men showed an increased incidence of depressive illness and a shorter time to diagnosis of depression,” the authors write. “Further prospective studies are needed to confirm these preliminary findings and to clarify the role of testosterone in the treatment of depressive illness in older men.”

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Article adapted by MD Only Weblog from original press release.
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Contact: Kris Connor (Arch Gen Psychiatry. 2004;61:162-167. Available at http://www.archgenpsychiatry.com)

Contact: Jeri Rowe
JAMA and Archives Journals

Exercise Reduces Muscle and Joint Pain 25%

People who exercise regularly experience 25% less muscle and joint pain in their old age than people who are less active. Research published in Arthritis Research & Therapy reveals that people who regularly participate in brisk aerobic exercise, such as running, experience less pain than non-runners even though they are more likely to suffer from pain from injuries.

Bonnie Bruce and colleagues from Stanford University, USA, compared the level of pain in a group of runners and a group of community-based individuals who acted as controls. Participants were followed for 14 years, and were on average in their mid-sixties when the study started. Each year, they completed a questionnaire about their health status, exercise habits and history of injuries. In total, the study included 866 subjects: 492 Runners’ Association members and 374 controls.

Bruce et al.’s results show that the greater majority of physically active participants did, on average, between 355 and 2,119 minutes of exercise per week over the course of the study, while controls exercised significantly less. After adjusting for confounding factors such as gender, age, weight and health status the results show that pain increased in both groups over time. But members of the Runners’ Association experienced 25% less musculoskeletal pain than controls. This reduction persisted throughout the study period, until the subjects reached an age of 62 to 76 years.

“Exercise was associated with a substantial and significant reduction in pain even [...] despite the fact that fractures, a significant predictor of pain, were slightly more common among runners,” conclude the authors.

More research is needed to investigate the mechanisms that might underlie the effect of exercise on musculoskeletal pain in old age.

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Article adapted by MD Only Weblog from original press release.
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Aerobic Exercise And Its Impact On Musculoskeletal Pain In Older Adults: A 14-Year Prospective, Longitudinal Study
Bonnie Bruce, James F. Fries, Deborah P. Lubeck
Arthritis Research & Therapy 2005, 7:R1263-R1270 (19 September 2005)

Juliette Savin
press@biomedcentral.com
44-207-631-9931
BioMed Central
http://www.biomedcentral.com

Arthritis Research & Therapy (http://arthritis-research.com/) is published by BioMed Central (http://www.biomedcentral.com), an independent online publishing house committed to providing open access to peer-reviewed biological and medical research. This commitment is based on the view that immediate free access to research and the ability to freely archive and reuse published information is essential to the rapid and efficient communication of science.

Little Children Not Getting Enough Fiber

A Penn State analysis of the diets of a nationally representative sample of U.S. preschoolers, ages 2 to 5, shows that more than three-quarters of the children are not getting enough fiber.

Children who consumed the most fiber also had the most nutrient-rich diets. However, all children in the study ate fewer dairy servings than recommended by the Food Guide Pyramid.

Dr. Sibylle Kranz, assistant professor of nutritional sciences who led the study, says, “There is clinical evidence that children with low fiber intakes are at risk of chronic constipation. However, there are also other reasons to encourage fiber consumption in children. For example, fiber has been shown to lower cardiovascular risk in adults. Children who eat high-fiber foods are more likely to grow up into adults who consume adequate fiber.”

The study detailed in the Journal of the American Dietetic Association in a paper, Dietary Fiber Intake by American Preschoolers is Associated with More Nutrient-Dense Diets. (view abstract) The authors are Kranz; Diane C. Mitchell, Penn State Diet Assessment Center coordinator; Anna Maria Siega-Riz, associate professor of maternal and child health, University of North Carolina, Chapel Hill; and Dr. Helen Smiciklas-Wright, Penn State professor of nutritional sciences.

In the study, dietary consumption estimates were based on 2-day averages of 5,437 children whose parents provided information in the 1994-1996 and 1998 Continuing Survey of Food Intake by Individuals conducted by the U.S. Department of Agriculture. The researchers conducted separate analyses on the 2 and 3 year olds and the 4 and 5 year olds and compared them.

The younger children had, on average, a higher fiber intake than the older children. The two and three year olds, whose fiber intake placed them in the top quarter of the sample, met the new National Academy of Sciences Dietary Reference Intake level. These guidelines propose that Americans of all ages consume 14 g total fiber per every 1,000 calories based on evidence for reduced cardiovascular disease risk at that level.

The main fiber sources consumed by the children were, in order: low-fiber fruits, such as applesauce; legumes; and high-fiber cereal. Other low-fiber, low-nutrient foods that contributed very small amounts of fiber to the children’s diets included pizza and other high-fat, grain-based mixed dishes and high-fat salty snacks such as chips. High-fiber vegetables and fruit, which should be a major source of fiber, were consumed in too small quantities to contribute to the total average fiber intake.

“If parents feed their preschoolers fiber-rich foods, they are most likely providing important nutrients for the children as well,” Kranz says. “An easy substitution to get more fiber into their diets is to change to whole-grain products and high-fiber cereals. Also, children usually like sweet potato, baked beans, grapes and oranges and they’re all high-fiber, high-nutrient foods.”

The study was supported by a seed grant from the Penn State College of Health and Human Development.

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Article adapted by MD Only Weblog from original press release.
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Source: Andrea Elyse Messer
Penn State

Children Don’t Drink Enough Milk

American children are drinking too little milk and what they are consuming is too high in fat, according to a Penn State study.”There is a strong correlation between dairy consumption and calcium,” says Sibylle Kranz, assistant professor of nutritional sciences. “While there is calcium in fortified orange juice, for example, it is not as bioavailable as that found in milk.” She notes that people need to take calcium with vitamin D and some protein for optimal use in the body.

Kranz, working with Po-Ju Lin, doctoral student and David A. Wagstaff, statistician, looked at children’s average daily dairy intake and compared it with that recommended by the U.S. Department of Agriculture’s My Pyramid dairy recommendations and Adequate Intake of calcium for various ages from 2 through 18. Their findings, reported online in press in the Journal of Pediatrics, are that only 2 to 3 year olds meet the MyPyramid dairy recommendations. They also noticed that most children choose to consume more of the highest fat varieties of cheese, yogurt, ice cream and dairy-based toppings.

The various recommendations for dairy intake in children established by a variety of organizations suggest two cups for 1 to 3 year olds, two to three cups for 4 to 8 year olds, and three to four cups for 9 to 18 year olds depending on the recommending agency.

Only the youngest age group met these requirements. Among 4 to 8 year olds, consumption dropped below two cups a day and remained steady for 9 to 13 year olds, and declined again among 14 to 18 year olds. All these dairy and calcium intake patterns were observed while the recommendation increased to three and then four cups daily.

“Although the recommendations are all for low fat dairy,” says Kranz. “People are still consuming great amounts of whole fat dairy products.”

The researchers found that 43 to 51 percent of the dairy consumed by younger children was from whole-fat sources with only 5 to 11 percent from non-fat dairy. Older children consumed about 35 to 36 percent from whole-fat dairy and 11 to 13 percent from non-fat dairy sources.

“A glass of fat-free milk has 80 calories, while whole milk has 150 calories,” says Kranz. “That is a difference per glass of 70 calories or 210 to 280 calories a day for individuals consuming three to four servings of dairy.”

The Penn State researcher notes that these additional calories can add to the current problems of childhood obesity. The difference between whole-fat and reduced-fat mozzarella cheese is 20 calories per ounce with another 30 calories if the cheese is fat free.

“While children are not meeting the diary or calcium requirements, it is not a good idea to try to meet them by eating premium ice creams or other high fat products,” says Kranz. She suggests frozen yogurts or sherbets or low or non-fat yogurt, cheese and toppings.

Also, researchers noted that dairy consumption patterns have not changed recently. Although physicians once recommended that children receive whole milk during the first year of life, that recommendation is no longer true. Doctors now recommend consumption of baby formula if the child is not nursing.

Starting with the second year of life, reduced-fat or fat-free milk is appropriate. However, children are still drinking whole-fat milk.

A cup of milk provides 250 to 300 milligrams of calcium, a cup of low-fat yogurt contributes about 400 milligrams of calcium and an ounce of cheese includes about 200 milligrams of calcium. In dairy products, about 32 percent of the calcium is bioactive and used by the body. Other sources of calcium such as soy milk and fortified orange juice at 300 milligrams are only about 25 percent available.

Dairy products in general are the best sources of calcium for children, but knowing this and getting children to eat more low-fat dairy options (yogurt, cheese and milk) are not the same thing.

Kranz suggests that one solution would be non-fat, non-sugared flavored milk products. These can range from milk with a little cocoa powder to milk blended with strawberries or blueberries.

Currently, only 9 percent of 2 to 3 year olds’ dairy consumption is flavored milk, 4 to 13 year olds drink more flavored milk –16 to 18 percent, while 14 to 18 year olds are at 13 percent.

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Article adapted by MD Only Weblog from original press release.
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Source: Andrea Elyse Messer
Penn State

“MIGHTY MICE” MADE MIGHTIER

The Johns Hopkins scientist who first showed that the absence of the protein myostatin leads to oversized muscles in mice and men has now found a second protein, follistatin, whose overproduction in mice lacking myostatin doubles the muscle-building effect.

Results of Se-Jin Lee’s new study, appearing on August 29 in the online, open-access journal PLoS ONE, show that while mice that lack the gene that makes myostatin have roughly twice the amount of body muscle as normal, mice without myostatin that also overproduce follistatin have about four times as much muscle as normal mice.

Lee, M.D., Ph.D., a professor of molecular biology and genetics, says that this added muscle increase could significantly boost research efforts to “beef up” livestock or promote muscle growth in patients with muscular dystrophy and other wasting diseases.

Specifically, Lee first discovered that follistatin was capable of blocking myostatin activity in muscle cells grown under lab conditions. When he gave it to normal mice, the rodents bulked up, just as would happen if the myostatin gene in these animals was turned off. He then genetically engineered a mouse that both lacked myostatin and made extra follistatin. If follistatin was increasing muscle growth solely by blocking myostatin, then Lee surmised that follistatin would have no added effect in the absence of myostatin.

“To my surprise and delight, there was an additive effect,” said Lee, who notes these muscular mice averaged a 117 percent increase in muscle fiber size and a 73 percent increase in total muscle fibers compared to normal mice.

“These findings show that the capacity for increasing muscle growth by targeting these pathways is much more extensive than we have appreciated,” adds Lee. “Now we’ll search for other players that cooperate with myostatin, so we can tap the full potential for enhancing muscle growth for clinical applications.”

Lee adds that this issue is of particular significance, as most agents targeting this pathway, including one drug being currently tested in a muscular dystrophy clinical trial, have been designed to block only myostatin and not other related proteins.

The research was funded by grants from the NIH and the Muscular Dystrophy Association and by a gift from Merck Research Laboratories.

See the following sites for more information:

http://www.jhu.edu/sejinlee/
http://www.plosone.org/home.action

Citation: Lee S-J (2007) Quadrupling Muscle Mass in Mice by Targeting TGF-ß Signaling Pathways.PLoS ONE 2(8): e789. doi:10.1371/journal.pone.0000789
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Vitamin D Deficiency a Common Problem in Children and Adults

In a review article to appear in the July 19th issue of the New England Journal of Medicine, Dr. Michael Holick, an internationally recognized expert in vitamin D, provides an overview of his pioneering work that expounds on the important role vitamin D plays in a wide variety of chronic health conditions, as well as suggesting strategies for the prevention and treatment of vitamin D deficiency.

Humans attain vitamin D from exposure to sunlight, diet and supplements. Vitamin D deficiency is common in children and adults. In utero and childhood, vitamin D deficiency may cause growth retardation, skeletal deformities and increase risk of hip fractures later in life. In adults, vitamin D deficiency may precipitate or exacerbate osteopenia, osteoporosis, muscle weakness, fractures, common cancers, autoimmune diseases, infectious diseases and cardiovascular diseases.

According to Holick, a professor of medicine, physiology, and biophysics, and director of the General Clinical Research Center at Boston University School of Medicine and Director of the Bone Healthcare Clinic at Boston Medical Center, it has been estimated that 1 billion people world-wide are vitamin D deficient or insufficient.

Without vitamin D only about 10-15 percent of dietary calcium and about 60 percent of phosphorus is absorbed by the body. This is directly related to bone mineral density which is responsible for osteoporosis and fractures, as well as muscle strength and falls in adults. In utero and childhood, calcium and vitamin D deficiency prevents the maximum deposition of calcium in the skeleton.

Studies have shown people living at higher latitudes (where the angle of the sun’s rays are unable to sufficiently produce adequate amounts of vitamin D in the skin) are more likely to develop and die of Hodgkin’s lymphoma, colon, pancreatic, prostate, ovarian, breast and other cancers. According to Holick, both prospective and retrospective epidemiologic studies have also shown an association between low levels of vitamin D and an increased risk for Type 1 diabetes, multiple sclerosis, Crohn’s disease, hypertension and cardiovascular disease.

Holick believes the current recommended Adequate Intakes for vitamin D need to be increased to 800 – 1000 IU vitaminD3/d. “However, one can not obtain these amounts from most dietary sources unless one is eating oily fish frequently,” says Holick. “Thus, sensible sun exposure (or UVB irradiation) and/or supplements are required to satisfy the body’s vitamin D requirement,” he adds.

Lastly Holick adds, “The goal of this paper is to make physicians aware of the medical problems associated with vitamin D deficiency. Physicians will then be able to impart this knowledge to their patients so they too will know how to recognize, treat and most importantly, maintain adequate levels of this important vitamin.”

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  Article adapted by MD Only Weblog from original press release.
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Reference: More information and complete text of the published article can be found at University of Boston..
Contact: Gina M. Digravio

Quadrupling Muscle Mass

Myostatin (MSTN) is a transforming growth factor-ß (TGF-ß) family member that plays a critical role in regulating skeletal muscle mass [1]. Mice engineered to carry a deletion of the Mstn gene have about a doubling of skeletal muscle mass throughout the body as a result of a combination of muscle fiber hyperplasia and hypertrophy [2]. Moreover, loss of myostatin activity resulting either from postnatal inactivation of the Mstn gene [3], [4] or following administration of various myostatin inhibitors to wild type adult mice [5]–[7] can also lead to significant muscle growth. Hence, myostatin appears to play as least two distinct roles, one to regulate the number of muscle fibers that are formed during development and a second to regulate growth of muscle fibers postnatally. The function of myostatin appears to have been conserved across species, as inactivating mutations in the myostatin gene have been demonstrated to cause increased muscling in cattle [8]–[11] , sheep [12], dogs [13] and humans [14]. As a result, there has been considerable effort directed at developing strategies to modulate myostatin activity in clinical settings where enhancing muscle growth may be beneficial. In this regard, loss of myostatin activity has been demonstrated to improve muscle mass and function in dystrophic mice [15]–[17] and to have beneficial effects on fat and glucose metabolism in mouse models of obesity and type II diabetes [18].

Myostatin is synthesized as a precursor protein that undergoes proteolytic processing to generate an N-terminal propeptide and a C-terminal dimer, which is the biologically active species. Following proteolytic processing, the propeptide remains bound to the C-terminal dimer and maintains it in an inactive, latent complex [6], [19], [20], which represents one of the major forms of myostatin that circulates in the blood [21], [22]. In addition to the propeptide, other binding proteins are capable of regulating myostatin activity in vitro, including follistatin [19], [21], FLRG [22], and Gasp-1 [23]. We previously showed that follistatin can also block myostatin activity in vivo; specifically, we showed that follistatin can ameliorate the cachexia induced by high level expression of myostatin in nude mice [21] and that transgenic mice expressing follistatin in muscle have dramatic increases in muscle mass [19]. Here, I show that overexpression of follistatin can also cause substantial muscle growth in mice lacking myostatin, demonstrating that other TGF-ß related ligands normally cooperate with myostatin to suppress muscle growth and that the capacity for enhancing muscle growth by targeting this signaling pathway is much larger than previously appreciated.

Results

Increased muscle mass in transgenic mice expressing FLRG

Previous studies have identified several proteins that are normally found in a complex with myostatin in the blood [22], [23]. One of these is the follistatin related protein, FLRG, which has been demonstrated to be capable of inhibiting myostatin activity in vitro. To determine whether FLRG can also inhibit myostatin activity in vivo, I generated a construct in which the FLRG coding sequence was placed downstream of a myosin light chain promoter/enhancer. From pronuclear injections of this construct, a total of four transgenic mouse lines (Z111A, Z111B, Z116A, and Z116B) were obtained containing independently segregating insertion sites. Each of these four transgenic lines was backcrossed at least 6 times to C57 BL/6 mice prior to analysis in order to control for genetic background effects. Northern analysis revealed that in three of these lines the transgene was expressed in skeletal muscles but not in any of the non-skeletal muscle tissues examined (Figure 1); in the fourth line, Z111B, the expression of the transgene was below the level of detection in these blots. As shown in Table 1, all four lines exhibited significant increases in muscle weights compared to wild type control mice. These increases were observed in all four muscles that were examined as well as in both sexes. Moreover, the rank order of magnitude of these increases correlated with the rank order of expression levels of the transgene; in the highest-expressing line, Z116A, muscle weights were increased by 57–81% in females and 87–116% in males compared to wild type mice. Hence, FLRG is capable of increasing muscle growth in a dose-dependent manner when expressed as a transgene in skeletal muscle.

The research was funded by grants from the NIH and the Muscular Dystrophy Association and by a gift from Merck Research Laboratories.

See http://www.jhu.edu/sejinlee/%20for%20more%20information for more information.
Citation: Lee S-J (2007) Quadrupling Muscle Mass in Mice by Targeting TGF-ß Signaling Pathways. PLoS ONE 2(8): e789. doi:10.1371/journal.pone.0000789

LINK TO THE PUBLISHED ARTICLE http://www.plosone.org/doi/pone.0000789

Source: Nick Zagorski
Johns Hopkins Medical Institutions

Repeated sessions of exercise burn more fat than a single, long session

BETHESDA, Md. (July 10, 2007) — Taking a break in the middle of your workout may metabolize more fat than exercising without stopping, according to a recent study in Japan.  Researchers conducted the first known study to compare these two exercise methods—exercising continually in one long bout versus breaking up the same workout with a rest period.  The findings could change the way we approach exercise.  Who wouldn’t want to take a breather for that? 

“Many people believe prolonged exercise will be optimal in order to reduce body fat, but our study has shown that repetitions of shorter exercise may cause enhancements of fat mobilization and utilization during and after the exercise. These findings will be informative about the design of [future] exercise regimens,” said lead researcher Kazushige Goto, Ph.D. “Most people are reluctant to perform a single bout of prolonged exercise. The repeated exercise with shorter bouts of exercise will be a great help [in keeping up with fitness].”

This finding is part of a study entitled Enhancement of fat metabolism by repeated bouts of moderate endurance exercise, found in the June 2007 edition of the Journal of Applied Physiology, which is published by the American Physiological Society. It was conducted by Kazushige Goto, of both the Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Tokyo, Japan and the Institute of Sports Medicine, Bispebjerg Hospital, Copenhagen, Denmark; Naokata Ishii, of the Department of Life Sciences, Graduate School of Arts and Sciences, University of Tokyo, Komaba, Tokyo, Japan; and Ayuko Mizuno and Kaoru Takamatsu, both of the Institute of Health and Sport Sciences, University of Tsukuba, Tsukuba, Ibaraki, Japan. 

Summary of Methodology

The researchers used seven healthy (avg. body mass: 66.1, percentage fat: 17.6) men with an average age of 25 who were physically active and familiar with exercise and had them perform three separate trials:

• one single bout of 60-min exercise followed with a 60-min recovery period (Single)
  
• two bouts of 30-min exercise with a 20-min rest after the first 30-min bout, along with a 60-min recovery period at the end (Repeated)
  
• one 60-min rest period (Control)
  

The men performed each trial at the same time of day after fasting overnight.  They exercised on a single ergometer (cycling machine) at the commonly recommended exercise prescription of 60% maximum oxygen intake.  The recovery and rest periods were conducted while the subjects sat in chairs.   Blood samples were taken every 15 minutes during the exercise and every 30 minutes during the recovery period.  Their respiratory gas and heart rates were monitored continuously throughout the trial.

Summary of Results

The Repeated trial showed a greater amount of lipolysis (fat breakdown) than did the Single trial.  This Repeated trial also had a pronounced increase in free fatty acids and glycerol (chemical compounds that are released when stored fat is used) concentrations in the final 15 minutes of exercise, whereas these concentrations only progressively increased throughout the Single trial.  Also, the second half of the Repeated trial showed a significantly greater epinephrine response while also having a rapid decrease in insulin concentration as a result of lower plasma glucose.  This combination of high epinephrine and low insulin concentration may have also increased the lipolysis.  There was also enhanced fat oxidation in the recovery period of the Repeated trial than in the Single trial, but this result may be because the free fatty acids concentration was already high before the recovery period.

Conclusions

The American College of Sports Medicine recommends moderate exercise for the duration of 45 to 60 minutes to ensure a sufficient amount of energy is depleted in obese individuals.  This has caused a greater focus on extending exercise sessions in order to burn more fat.  However, this study shows that this method may not be the most effective way to enhance fat metabolism, as splitting up a long bout of exercise with a rest period burns more fat than a continuous bout of exercise.  This study could help with the practical application of implementing new exercise methods in order to better manage and control weight in individuals in the future.  However, Goto and his team of researchers plan on conducting further studies in order to explore the results in a variety of exercise durations as well as in different types of individuals.

SOURCE: Journal of Applied Physiology, June 2007

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Drinking Milk After Exercise Encourages Muscle Gain And Fat Loss, Study Finds

Part of an ongoing study into the impact of drinking milk after heavy weightlifting has found that milk helps exercisers burn more fat.

The study by researchers at McMaster University and published in the American Journal of Clinical Nutrition, was conducted by the Department of Kinesiology’s Exercise Metabolism Research Group, lead by Stuart Phillips.

The researchers took three groups of young men 18 to 30 years of age — 56 in total — and put them through a rigorous, five-day-per-week weightlifting program over a 12-week period. Following their workouts, study participants drank either two cups of skim milk, a soy beverage with equivalent amounts of protein and energy, or a carbohydrate beverage with an equivalent amount of energy, which was roughly the same as drinking 600 to 700 milliliters of a typical sports drink.

Upon the study’s conclusion, researchers found that the milk drinking group had lost nearly twice as much fat – two pounds – while the carbohydrate beverage group lost one pound of fat. Those drinking soy lost no fat. At the same time, the gain in muscle was much greater among the milk drinkers than either the soy or carbohydrate beverage study participants.

“The loss of fat mass, while expected, was much larger than we thought it would be,” says Phillips, associate professor of kinesiology at McMaster. “I think the practical implications of these results are obvious: if you want to gain muscle and lose fat as a result of working out, drink milk.”

As reported in the first phase of the study, the milk drinking group came out on top in terms of muscle gain with an estimated 40 per cent or 2.5 pounds more muscle mass than the soy beverage drinkers. In addition, this group gained 63 per cent or 3.3 pounds, more muscle mass than the carbohydrate beverage drinkers.

“I think the evidence is beginning to mount,” says Phillips. “Milk may be best known for its calcium content in supporting bone health, but our research, and that of others, continually supports milk’s ability to aid in muscle growth and also promote body fat loss. To my mind — with milk being a source of nine essential nutrients — it’s a no brainer: milk is the ideal post-workout drink for recreational exercisers and athletes alike.”

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Article adapted by Medical News Today from original press release.
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Ongoing work with this project will focus on the components of milk that might be responsible for the effects observed by the McMaster-based researchers. The work was supported by grants from the Canadian Institutes for Health Research and a grant from the US National Dairy Council.
Source: Stu Phillips
McMaster University

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Article URL: http://www.medicalnewstoday.com/articles/79235.php