Eating more protein but less fats helps reduce daily total energy intake, researchers say in a new report in Public Health Nutrition. The effect is substantial. A 10% increase in protein intake accompanied by a 10% drop in fats reduced daily total calories by 26%, 28%, and 32% in normal-weight, overweight, and obese men, and by 27%, 27%, and 29% in normal-weight, overweight, and obese women, the researchers report.
“Obesity rates in the U.S. have been going up for decades, and excess calorie intake remains the fuel”, said University of Illinois kinesiology and community health professor Ruopeng An, who led the new analysis, “Numerous fad diets and best-selling books on diet and weight loss prevail, making different and often conflicting suggestions. However, many of these claims are either not scientifically tested, or come from small-scale experiments which are not generalizable to the general population. Obesity is an epidemic, and thus public policies to combat obesity should be informed by population level studies.”
An and his colleague Nicholas Burd analyzed a decade of dietary interview data from a nationally representative health survey on the American population. “Across all population subgroups, substituting protein or carbohydrates for fats and substituting protein for carbohydrates were associated with decreased daily energy intake, with the largest effect resulted from substituting protein for fats.” They wrote. In contrast, substituting fats or carbohydrates for protein and substituting fats for carbohydrates led to increased calorie intake.
The reason why substituting protein for fats or carbohydrates helps reduce total energy intake potentially lies in its effect on improved satiety and thermogenesis. Research has shown that protein may satisfy hunger better than either fats or carbohydrates.” Said Burd, “The sooner your appetite feels full, the earlier you will stop eating and ultimately this will lead to less calories being consumed over the course of a day.” There are other reasons for promoting protein at the expense of fat intake, as noted in the study, such as improved bone health and reduced risk for cardiovascular disease.
American dietary guidelines recommend a variety of protein foods – seafood, lean meat and poultry, eggs, beans and peas, soy products, and unsalted nuts and seeds, whereas protein foods high in solid fats are discouraged. “A possibly less emphasized point is the importance of substitution between macronutrients (protein or carbohydrate for fat, and protein for carbohydrate) because eating extra protein when already consuming very high caloric diets from fat or carbohydrate will make it very difficult to facilitate weight loss as it will simply increase overall daily calorie intake”
An and his colleague wrote, “If increased consumption of protein products is not accompanied by a proportional reduction in fat intake, daily total energy consumption would only increase, so that the modification in dietary profile is unlikely to translate to healthier weight status.”
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