How Nutrition Affects The Breakdown Of Fats
Science Daily — Scientists have shown that when either lean or obese individuals exercise after eating a high fat meal, their fats are broken down and oxidized in skeletal muscle, making them healthier. These results show for the first time how a high fat diet and exercise stimulate the breakdown of fats and may help design ways to reduce excessive fat in the body.
Fat is broken down inside fat cells to generate energy by a process called lipolysis. The resulting fatty acids are released into the bloodstream and carried to tissues that require energy. In obese individuals, too much fat accumulates, compromising lipolysis, but the details of how this happens are not well understood. Also, obese individuals can show altered responsiveness to the stress hormones epinephrine and norepinephrine in their subcutaneous fat.
Max Lafontan and colleagues investigated how fat is broken down in both lean and obese subjects who exercised after either fasting or eating a high-fat diet. They noticed that after eating a high-fat diet, fats were broken down in both lean and obese individuals. Under fasting conditions, the breakdown of fats was more pronounced in the lean subjects, but the high fat meal enhanced lipolysis in the obese subjects.
The scientists also studied the effects of long-chain fatty acids (LCFAs) -- which are found in high fat diet -- on cultured fat cells. They noticed that LCFAs increase lipolysis when it is induced by epinephrine, one of the hormones known to stimulate lipolysis.
By showing for the first time how a high fat diet and LCFAs affect hormone-induced lipolysis in fat cells, this study paves the way for further research on the role of various fatty acids on the metabolism of muscle and blood vessel cells, the researchers conclude.
Article: "Acute exposure to long-chain fatty acids impairs alpha2-adrenergic receptor-mediated antilipolysis in human adipose tissue," by Jan Polak, Cedric Moro, David Bessiere, Jindra Hejnova, Marie A. Marques, Magda Bajzova, Max Lafontan, Francois Crampes, Michel Berlan, and Vladimir Stich
Note: This story has been adapted from a news release issued by American Society for Biochemistry and Molecular Biology.
Alternate-day Fasting: How Good Is It For Your Health?
Science Daily — Researchers report that fasting or eating half as much as usual every other day may shrink your fat cells and boost mechanisms that break down fats.
Consuming less calories and increasing physical activity is usually what people do to lose weight and stay healthy. But some people prefer to adopt a diet which consists of eating as much as they want one day while fasting the next. On each fasting day, these people consume energy-free beverages, tea, coffee, and sugar-free gum and they drink as much water as they need.
Although many people claim that this diet, called alternate-day fasting (ADF), help them lose weight and improved their health, the effects on health and disease risk of ADF are not clear.
Krista Varady and colleagues studied the effects of alternate-day fasting on 24 male mice for four weeks. To assess the impact of ADF on the health of the mice, the scientists not only tested mice that followed and didn't follow an ADF diet, but they also studied mice that followed the diet only partially: a group of mice consumed 50 percent of their regular diet every other day (ADF-50%) and another consumed 75 percent of their regular diet every other day (ADF-25%).
The scientists noticed that the ADF-100% mice lost weight and the fat cells of both the ADF-100% and ADF-50% groups shrunk by more than half and by 35 percent, respectively. Also, in these two groups of mice, fat under the skin -- but not abdominal fat -- was broken down more than in mice that did not follow the diet.
These results suggest that complete and modified ADF regimens seem to protect against obesity and type 2 diabetes but do not result in fat or weight loss. More studies will be needed to confirm whether the long-term effects of ADF regimens are beneficial for health and reduce disease risk, the scientists conclude.
Article: "Effects of modified alternate-day fasting regimens on adipocyte size, triglyceride metabolism and plasma adiponectin levels in mice," by Krista A. Varady, D. J. Roohk, Y. C. Loe, B. K. McEvoy-Hein, and M. K. Hellerstein
Note: This story has been adapted from a news release issued by American Society for Biochemistry and Molecular Biology.
