Too much emphasis on breakfast when dieting will cost you muscle mass


If you want to lose weight you need to make sure you get a good breakfast. Try asking Google. But a small study done in 1997 showed that athletes may not be taking the best approach to dieting if they put too much emphasis on breakfast. Doing this means you lose lean body mass – in other words muscle mass.

Seventies study
In the 1970s researchers did experiments in which they gave their subjects just one meal a day. [Chronobiologia 1975; 2(suppl 1): 33.] The meal provided just enough calories to maintain body weight. When the subjects ate their meal in the evening they maintained the same weight. When they ate their meal in the mornings they lost a little weight.

Since that experiment, nearly all real and self-appointed slimming experts will tell you have to eat breakfast if you want to lose weight. The more of your daily calories you consume in the morning, the more of those calories you’ll burn, the story goes. The more calories you eat early in the morning, the higher your rate of metabolism and the more calories you burn. Ergo: breakfasting makes you slim.

Too much emphasis on breakfast when dieting will cost you muscle mass
In bodybuilding manuals you sometimes come across advice to strength athletes to “eat breakfast like a king, lunch like a prince and dinner like a pauper”. This was often accompanied by a photo of a broad-shouldered grinning hulk sitting at a table in front of a couple of pints of milk, a bunch of bananas, four kilograms of cottage cheese, a hunk of raw meat, a plate of brown rice and a couple of dozen boiled eggs. And the caption would be: A strength athlete’s day starts with a good breakfast.

1997 study
Unfortunately the researchers in the seventies didn’t look at body composition. Nutritionists at the American department of agriculture did look at this in their experiments, however. In 1997 they published in the Journal of Nutrition the results of a study in which they had got 10 women to lose weight on a not too strict diet in which the women were given 2 meals a day – breakfast and dinner.

The women were divided into 2 groups. One group followed the AM-pattern for the first 6 weeks of the study. For this the women consumed 70 percent of their daily calorie intake at breakfast. The other half followed the PM-pattern, consuming 70 percent of their daily calories at dinner.

After 6 weeks the women changed over their eating pattern. The women who had started with the AM-pattern then did 6 weeks on the PM-pattern; the women who had started with the PM-pattern did the next 6 weeks on the AM-pattern.



The graphs above show you how much weight, fat mass and lean body mass the women lost during the experiment.

These graphs summarise the most important findings from the study. They show the average body weight development and body composition during 6 weeks of dieting on the PM- and AM-patterns.

If weight loss alone is your main goal, then a good breakfast and a light dinner is an option. But if you want to lose weight but not too much muscle mass, you are better off with a light breakfast and consuming most of your calories in the evening.

Weight loss is greater with consumption of large morning meals and fat-free mass is preserved with large evening meals in women on a controlled weight reduction regimen.


The purpose of this study was to determine whether meal ingestion pattern [large morning meals (AM) vs. large evening meals (PM)] affects changes in body weight, body composition or energy utilization during weight loss. Ten women completed a metabolic ward study of 3-wk weight stabilization followed by 12 wk of weight loss with a moderately energy restricted diet [mean energy intake +/- SD = 107 +/- 6 kJ/(kg.d)] and regular exercise. The weight loss phase was divided into two 6-wk periods. During period 1, 70% of daily energy intake was taken as two meals in the AM (n = 4) or in the PM (n = 6). Subjects crossed over to the alternate meal time in period 2. Both weight loss and fat-free mass loss were greater with the AM than the PM meal pattern: 3.90 +/- 0.19 vs. 3.27 +/- 0.26 kg/6 wk, P < 0.05, and 1.28 +/- 0.14 vs. 0.25 +/- 0.16 kg/6 wk, P < 0.001, respectively. Change in fat mass and loss of body energy were affected by order of meal pattern ingestion. The PM pattern resulted in greater loss of fat mass in period 1 (P < 0.01) but not in period 2. Likewise, resting mid-afternoon fat oxidation rate was higher with the PM pattern in period 1 (P < 0.05) but not in period 2, corresponding with the fat mass changes. To conclude, ingestion of larger AM meals resulted in slightly greater weight loss, but ingestion of larger PM meals resulted in better maintenance of fat-free mass. Thus, incorporation of larger PM meals in a weight loss regimen may be important in minimizing the loss of fat-free mass. PMID: 9040548 [PubMed - indexed for MEDLINE] Source: