Dietary Proteins and Weight Management

Dietary Proteins and Weight Management

Proteins and weight management

Protein is one of the major nutrients in our food and it is the building block of every cell in our bodies. Some of its properties are widely known: it contributes to the growth and maintenance of muscle mass, it is needed for building and repairing body tissue, and it functions as enzymes and hormones while contributing to the smooth running of the immune system¹. However, proteins have another key role in nutrition; they could also be helpful in managing body weight.

Observational studies have shown that diets high in protein are associated with a lower BMI* (Body Mass Index) and waist circumference². In addition, scientific evidence suggests that low calorie high protein diets are more effective than low calorie standard protein diets when it comes to weight loss and fat mass reduction as well as the maintenance of fat free mass^2-7.

* BMI is a measure that uses your height and weight to assess if your weight is within healthy parameters

Moreover, studies have also shown that after initial weight loss, high protein diets are thought to be more likely to prevent the lost weight from returning coming back, thus making weight management easier^{3, 8}.

Some of the possible mechanisms for explaining these effects are increased satiety and diet induced thermogenesis, and the maintenance of muscle mass that comes with high protein diets.

Appetite control

Several studies have demonstrated that proteins assist us in feeling fuller, preventing hunger-like symptoms for longer periods of time than carbohydrates and fats⁹. This is mainly due to the influence of protein consumption on appetite and satiety regulating hormones^10-12.

However, the contribution of proteins to satiety is not only evident in the more intense and longer-lasting feeling of fullness that follows the consumption of a high protein meal; protein rich diets may induce satiety in the medium term as well ^12,13, which may translate into reduced caloric intake. As some studies have shown, high protein diets could lead to a calorie intake reduction of up to 440 Kcal per day¹⁴.

Additionally, high protein diets have shown to have a greater effect in reducing the desire to eat late at night and reduce the craving for food than standard protein diets. This could be of value in helping to avoid overeating in the evenings and cutting down on late-night snacking¹⁵.

Increased Diet Induced Thermogenesis

When examining the properties of protein, it is also important to consider to thermic effect protein has during the digestive process. Diet Induced Thermogenesis, also known as Thermic Effect of Food, is the amount of energy needed to digest, absorb, and metabolize nutrients. It represents around 10% of the total daily energy consumption of the human body. It is influenced by the energy density and macronutrient composition of a meal. Protein generates a greater thermic effect of food than carbohydrates or fats. In fact, the thermic effect of proteins is up to ten times higher than fats, and three times higher than with carbohydrates³. This means that the body burns more calories when processing proteins than processing fats or carbohydrates.

The role of muscle mass

Muscle mass burns three times more calories per day than body fat. Each kilogram of muscle in the human body burns about 14Kcal per day, while fat only burns 4.5 Kcal per day¹⁶. Therefore, maintaining (or increasing) muscle mass, is key to boosting energy consumption throughout the day. However, anybody who embarks on a weight loss focused diet will find that one of the main challenges is to encourage loss of fat mass while maintaining lean muscle mass. Several studies have shown that, while inducing more weight and fat mass loss, high protein diets are also helpful for maintaining muscle mass⁶.

In addition to exercising, one of the major stimuli for muscle mass build up is the appropriate protein intake. When it comes to building muscle, not only the amount of protein consumption is important but the quality, timing and distribution of protein during the day. Several studies have shown that for better muscle stimuli, around 20 g of high quality protein should be consumed per meal, especially after an exercise bout^17-21. Besides, another study have also revealed that an even distribution of protein intake during the day (e.g., 30 g/meal) is more beneficial than skewed amounts of protein intake (e.g., 10 g for breakfast, 20 g for lunch, and 60 g for dinner) in promoting building muscle mass²².

Yet and despite scientific studies the average protein intake distribution of adults is often skewed, with a low intake at breakfast, which does not reach the threshold of 20–30 g, and is typically too much at dinner time ²³.

Sources of protein

The benefits of protein in managing appetite and weight are evidenced regardless of whether the protein comes from animal or plant l sources²⁴. Recommended sources of protein are lean meats, fish, low-fat dairy, eggs, soy and other legumes, and protein rich food supplements.

References:

1. Institute of Medicine. Dietary Reference Intakes for Energy, Carbohydrate, Fiber, Fat, Fatty Acids, Cholesterol, Protein, and Amino Acids. 2005. Washington, DC: The National Academies Press. https://doi.org/10.17226/10490.
2. Pasiakos SM, Lieberman HR, Fulgoni VL. Higher-protein diets are associated with higher HDL cholesterol and lower BMI and waist circumference in US adults. J Nutr. 2015 Mar;145(3):605-14.
3. Leidy HJ, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr 2015;101(Suppl):1320S–9S.
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