People interested in promoting an anabolic effect in muscle are often advised to eat small meals at frequent, regular intervals. The usual advice involves getting some form of protein at least every two to 2 1/2 hours to maintain optimal amino acid plasma levels, which promote the positive nitrogen retention most conducive to muscular growth. In practice, many bodybuilders try to eat four to eight small meals daily, which may not consist of solid foods but may instead be some type of protein drink.
Eating smaller meals more often is a good idea for several reasons. Besides maintaining a more positive nitrogen balance, smaller meals also allow you to eat more calories a day with less chance of bodyfat synthesis. Studies have repeatedly shown that the identical number of calories divided over four or more meals results in less bodyfat gain than the same calories consumed in two meals. That has to do with a more controlled insulin release.
Large meals promote greater insulin release, and insulin, in turn, favors storing calories as fat. Less insulin secreted per meal generally means less fat synthesized. A notable exception to the rule occurs within two hours following a workout. At that time a higher insulin secretion'as occurs when you take in a protein-and-simple carb drink'helps to speed muscle recovery through faster muscle glycogen synthesis and greater amino acid uptake.
While eating smaller high-protein meals more often does make sense, recent evidence shows that it may not apply to older people. A study of older women published last year found that the subjects had higher nitrogen retention and protein synthesis if they ate all their protein in only two meals, which is known as the 'pulse pattern' of eating.1 That occurs because it takes a higher level of free amino acids in the blood to promote protein synthesis in older people. Surprisingly, while most processes in the body slow with age, it turns out that amino acid extraction in the intestine increases.
The greater degree of protein absorption from meals in older people leads to a higher blood amino acid level, which is required to promote protein synthesis reactions. That explains the paradoxical finding that eating fewer meals increases protein synthesis in older people.
The same group of French researchers who discovered the 'aging effect' of protein retention recently investigated the effects of eating protein meals in fewer or more frequent feedings in a group of 16 women with an average age of 26.2 After a 15-day adaptive period the women ate a diet containing 1.7 grams of protein per kilogram of fat-free mass for two weeks. They ate the protein in either one or four meals.
While previous studies had shown that eating smaller, more frequent protein meals did lead to greater nitrogen retention in younger people, the new study found no significant difference between eating all your protein in one meal or eating it over four meals. Common sense would indicate that if younger women could not absorb amino acids with the same efficiency as their older counterparts, spreading the protein over several meals would lead to greater nitrogen retention, but that wasn't the case.
There wasn't any discussion of the physical activity levels of the young female subjects in this study. I would hazard a guess that if they were engaged in, for example, high-intensity weight training, getting more frequent protein meals would provide more beneficial effects than eating all their protein in one sitting. I base that on previous studies showing that muscle protein synthesis peaks within 48 hours after a weight-training session. It seems obvious that consuming a steady intake of amino acids'which are the core factors of upgraded muscle protein synthesis'would make sense under such exercise conditions.
Thus, the results of the new study may be more applicable to female couch potatoes than physically active young women. The findings for older women may still apply: They may be better off getting the majority of their protein in fewer meals to promote the upgraded blood amino acid levels that appear to be necessary for protein synthesis in older people. IM
1 Arnal, M.A., et al. (1999). Protein pulse feeding improves protein retention in elderly women. American J Clinical Nutrition. 69:1202-1208.
2 Arnal, M.A., et al. (2000). Protein feeding pattern does not affect protein retention in young women. J Nutrition. 130:1700-1704.