Importance of protein intake in weight loss
Obesity has been increasing at an unprecedented rate in the United States and the rest of the world. There are approximately 65% of people in the US who are overweight and 33% are clinically obese. This trend is also increasing among children and adolescents. Due to other health problems related to excess body weight, such as high cholesterol, high blood pressure, diabetes, and cardiovascular disease, obesity is perceived as an epidemic.
In recent years, there has been a significant discussion about the effect of protein-rich foods on weight loss. The first person to suggest this correlation was Dr. Atkins through his Atkins diet program. This started a series of marketing campaigns by the food industry promoting their protein-rich foods. These marketing pushes seem to have brought about a misconception among the common public that any food rich in protein would help with weight loss. This article highlights the importance of protein nutrition for general health and well-being along with its role in weight regulation.
A good protein intake is required for optimal health as our muscles, which make up around 40-50% of human body mass, are primarily made up of protein. Proteins are made of amino acids, which are therefore building blocks for the human body. The amino acids provided by dietary protein are necessary for the synthesis of body proteins in muscles, organs, bones, and skin, and for the synthesis of enzymes, certain hormones, antibodies, and a host of specialized products. Certain amino acids are essential for the proper functioning of the body and brain, such as tryptophan found in corn. Furthermore, proteins are essential as various specific proteins produced as a result of gene expression carry out all the general functioning of the body. That is, the gene pool of the human body that is made up of DNA and its associated genes gives rise to specific proteins that carry out their individual functions. Deficiencies in protein or in one or more of the essential amino acids cause reduced growth in children or loss of muscle mass in adults.
A high-protein diet has been linked to weight loss and maintenance in several recent studies. Protein keeps the body satisfied for longer, the feeling of satiety. There is compelling evidence that higher protein intake increases thermogenesis (the process of burning fat to produce body heat) and satiety compared to lower protein diets. The weight of evidence also suggests that protein-rich meals lead to reduced energy intake afterwards. Some evidence also suggests that high protein diets result in greater weight loss and fat loss compared to low protein diets. (1).
Protein plays a key role in regulating food intake through satiety related to diet-induced thermogenesis. Protein also plays a key role in regulating body weight through its effect on thermogenesis and body composition. A high percentage of energy coming from dietary protein limits the (re)gain of body weight through its satiety and energy inefficiency related to the change in body composition. (two)
Recently, Dr. Frank Hu of the Harvard School of Public Health, Boston, Massachusetts, published a review on the effects of high-protein diets on weight loss (1). The following are the key points of this review:
o Although authors of some fad diets have advocated increasing protein in the diet for weight loss, studies investigating the effects of high-protein diets on weight loss have only recently begun.
o There is convincing evidence that protein has a greater thermic effect compared to fat and carbohydrates. The evidence is also compelling that high protein diets increase satiety compared to low protein diets.
o High protein diets may facilitate weight loss compared to a low protein diet in the short term (within 6 months). But long-term data is limited.
o Exchanging protein for carbohydrates has been shown to improve blood lipids, and in epidemiological studies, diets high in protein have been associated with lower blood pressure and reduced risk of coronary heart disease.
o Although the optimal amount and sources of protein cannot be determined at this time, the weight of evidence suggests that in dietary practice, it may be beneficial to partially replace refined carbohydrates with protein sources low in saturated fat.
In short, good protein nutrition is essential for muscle mass and essential amino acids in the body. Furthermore, high protein intake appears to have an effect on weight loss and maintenance due to its effect on satiety and thermogenesis. However, a careful selection of protein-rich foods should be made, as protein-rich foods are also generally high in fat, for example, red meats such as beef and pork. If the diet must be modified to include protein-rich foods, the selection criteria should include plant-based food sources, such as soybeans, beans, legumes, as they are generally low in fat. Good sources of animal protein are fish and chicken, as they are generally low in saturated fat and high in unsaturated fats, such as omega-3 fatty acids.
References:
1. Halton H. and Hu F. (2004) The effects of high-protein diets on thermogenesis,
Satiety and weight loss: a critical review. Journal of the American College of Nutrition, Vol. 23(5):373-385.
2. Westerterp-Plantenga MS (2003) The importance of protein in food intake and regulation of body weight. Curr Opin Clin Nutr Metab Care. Flight. 6(6):635-8.