exercise may be more effective when coupled with a protein-rich diet

A new study conducted at the University of Illinois shows an additive, interactive effect when a protein-rich diet, with a macronutrient distribution within the acceptable range established by the Institute of Medicine, is combined with exercise. Energy restriction is generally considered the most important factor in a weight-loss diet, but the optimal macronutrient distribution has been disputed. This study adds to the evidence that higher protein levels and reduced carbohydrates in the diet not only aid weight loss but also preserve lean mass. Coupled with exercise, results were even more beneficial. Combining the two regimens, protein-rich diet with exercise, was additive for improving body composition.

The study was a randomized 4-month weight-loss trial using a 2 X 2 block design (diet X exercise).  Diet treatments provided 1700 kcals/day and consisted of either a low carbohydrate:protein ratio or a high carbohydrate:protein ratio. Exercise treatments consisted of either light walking activity or a walking requirement of 5 days/week plus 2 sessions/week of resistance training.

All groups lost significant weight during the 4-month treatment.  Subjects on the protein-rich diet plus exercise lost the most weight (11.2% of initial weight) with subjects on the high carbohydrate diet showing the least relative weight loss (8.4% of initial weight). While most of the weight loss was fat mass on all diets, the protein-rich diet and the exercise showed increased association with fat loss. The exercise program had a significant positive effect on lean mass, though the protein diet alone also showed a beneficial trend.

Initial serum lipids were similar among groups. All groups showed a change in blood lipid profiles at treatment's end, but the pattern of change differed depending on the diet regimen.  Changes in total cholesterol and LDL-C were greater in the carbohydrate and the carbohydrate plus exercise group. Changes in serum triacylglycerol were greater in the protein and protein plus exercise groups.  HDL-C concentrations changed in opposite directions in the two treatments producing a significant effect.  Protein groups showed an increase while carbohydrate groups decreased.

Citation:
Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women.  Sayman DK, Evans E, Baum JI, Seyler J, Erickson DJ, Boileau RA. Journal of Nutrition:Aug;135(8):1903-10.

To read the abstract, go to Abstract: Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women

To read the full article, go to Dietary Protein and Exercise Have Additive Effects on Body Composition during Weight Loss in Adult Women

Go to Protein-Rich Diet Boosts Benefit of Exercise to download a consumer tip sheet on how to fit lean protein in the diet.

higher protein diets May prove most beneficial when triacylgleycerol concentrations are high

A study published in the American Journal of Clinical Nutrition explored the effect of a reduced-caloric and low-fat intake associated with either a higher protein diet (protein - 34% of energy, carbohydrate - 46% of energy, fat - 20% of energy, saturated fat <10% of energy) or a higher carbohydrate diet (protein - 17% of energy, carbohydrate - 64% of energy, fat - 20% of energy, saturated fat <10% of energy) on weight loss, body composition, cardiovascular disease risk, nutritional status and markers of bone turnover in obese women.

Though there was no statistically significant difference in weight loss between diet groups, subjects with an initial high triacylglycerol status, one of the key markers of insulin resistance syndrome, lost 50% more total fat with the higher protein diet than with the higher carbohydrate diet. Women with high triacylglycerol concentrations on the high protein diet lowered their triacylglycerol levels significantly, by 28%, compared with only 10% for those on the higher carbohydrate diet.  Concerns that diets high in meat protein may have a negative effect on renal function and bone turnover were not substantiated.  The greatest difference in nutritional status observed between the two diets was the 9% increase in serum vitamin B12 status on the higher protein diet compared to a 13% decrease on the higher carbohydrate diet.

Citation:
Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women. Noakes M, Keogh JB, Foster PR, Clifton M. American Journal of Clinical Nutrition:2005;81(6):1298-306.

To read the abstract, go to Effect of an energy-restricted, high-protein, low-fat diet relative to a conventional high-carbohydrate, low-fat diet on weight loss, body composition, nutritional status, and markers of cardiovascular health in obese women

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