Protein and Meal Frequency Impact Weight Loss

Summary
There are innumerable diets prescribed for weight management. Eating a high protein diet plus consuming frequent small portions throughout the day are two common dietary plans given to obese people. This study found that a high protein content increases the sensation of fullness and affects satiety. It does not however affect appetite. Similarly, increasing the frequency of eating does not affect the appetite. Further research might help in understanding the mechanism responsible for these effects. Further research might also indicate the contribution of individual contents like carbohydrates in inducing satiety.

Introduction
A high protein diet is widely prescribed for weight management and promoting healthier diet options. Previous studies have indicated that increased dietary protein produced better control over appetite and a feeling of satiety. However, findings differed across studies. Some studies maintained that the high protein diet just created feelings of fullness and did not reduce appetite. Another dietary tactic commonly prescribed for weight management is to have frequent small meals. This study determined the effects of increased dietary protein and greater eating frequency on appetite and satiety. The study was carried out on obese men who continued their routine daily activities, unlike similar studies performed in the laboratory.

Methodology
* The study was planned for 12 weeks. Eligible obese, non-dieting male participants received a diet that was 750 calories/day lower than their usual daily energy intake.
* The participants were divided in two groups. The normal protein group received a diet containing 14 percent protein while the high protein group received a diet containing 25 percent protein.
* During the study, the participants consumed frequent meals for two weeks. Some ate three times in 15 hours while others ate six times in 12 hours. The total daily calorie intake however remained unchanged.
* The participants indicated their sensations of hunger, fullness, desire to eat and preoccupation with thoughts of food by answering a questionnaire.

Results
* Preoccupation with thoughts of food was lower in the group receiving high protein. The high protein group also consumed a much lower amount of carbohydrates at the same time.
* There was no difference in the daily hunger and desire to eat between the groups who consumed their daily food in three divided portions or in six divided portions.
* The high protein group experienced greater daily fullness as compared to the normal protein group but morning fullness was lower in the high protein group.
* In the high protein group, eating the daily quota of food in six portions at an interval of two hours led to a reduced sensation of evening fullness and late-night fullness.

Shortcomings
The study examined the effects of frequency of eating on satiety and appetite for a short period of two weeks. The findings obtained in a short-term study might not be relevant for long-term dietary management. The study was not performed in the laboratory. Blood samples from participants were not collected; these could have helped in understanding physiological mechanisms like hormonal changes responsible for inducing satiety and a sensation of fullness after eating a high protein diet.

Conclusions
The current study showed that eating a diet with higher protein content increased the sensation of fullness throughout the day. The findings of past studies testing the effect of a high protein diet were similar. It does seem that satiety is affected by the contents of food. A high protein content did not affect appetite and nor did the frequency of eating in a day. These findings suggest that satiety appears to be influenced by meal-related factors such as increased protein, while appetite might be driven by environmental, social and behavioral factors. In this study, high protein content meant correspondingly low carbohydrate content in the diet providing the same energy. More research might be required to decide whether the low carbohydrate percentage rather than the high protein percentage in the diet was responsible for the effects mentioned in this study.

For More Information:
The Effects of Consuming Frequent, Higher Protein Meals on Appetite and Satiety During Weight Loss in Overweight/Obese Men
Publication Journal: Obesity, April 2011
By Heather J. Leidy; Minghua Tang; Purdue University, West Lafayette, Indiana

*FYI Living Lab Reports Are Summaries of the Original Research.
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