Role of Protein in Fat Loss

Obesity has become a major concern not only in India but also globally. It is well recognized that obesity increases the risk of diseases like diabetes, hypertension, etc. It also has negative consequences on the emotional well-being and quality of life of the general public. The two most important factors that lead to a rise in obesity nowadays are the sedentary lifestyle and overeating habits among others. Many of us put a lot of effort into reducing our body weight.

You may hit the gym regularly and follow your fitness regime perfectly. You may even go on a calorie deficit diet for the same. But, do you know that one of the major macronutrients which you need to pay attention to while on a calorie deficit is your protein? Your calorie deficit may not help you in your weight loss journey if you are not consuming adequate amounts of proteins.

Read more to know why protein intake is vital for weight loss and why is it necessary to consume proteins while on a calorie deficit for weight loss.

Body Recomposition during Weight Loss

You need to understand that when on your weight loss journey, you not just lose fat mass but your body composition also goes on changing. It was seen in earlier studies that initial weight loss interventions were designed around dietary changes and calorie restrictions. These interventions mainly focused on total weight loss rather than body composition changes. This was a wrong approach because more important than overall weight loss is, sustainably losing only fat mass (FM) while maintaining the lean body mass (LBM). (1)

Now, your lean body mass includes the mass of your body organs, skin, bones, body water as well as muscle mass. Losing lean body mass has proven to have numerous detrimental effects on health and on the body’s ability to conduct various daily activities. It also has a negative impact on emotional and psychological states. Reduced LBM increases fatigue throughout the day and may even lead to an increase in the risk of injuries. (2,3)

Moreover, due to the loss of LBM your metabolic rate will also decrease and this may lead to regaining and overshooting of fat mass as soon as you go back to your normal calorie intake. Thus, maintaining your weight loss becomes problematic. Therefore, to enhance the sustainability of any weight loss program, and to offset any potential negative health consequences, it is important to prevent the loss of LBM.

Role of Protein in preventing loss of LBM

Various studies have shown that maintaining an adequate intake of proteins while on calorie deficit has helped in preventing the loss of lean body mass. 

A study was conducted among older women above 60 years of age, who were either overweight or obese had all the participants consuming a diet of 1400 calories (with fixed macros). Then, 50 g of protein was added to this diet for one group and 50 g of carbohydrates for another. When muscle gain was measured relative to body fat loss, not surprisingly, the protein group won! (4)

Another study conducted among 130 overweight people who were divided between a high-protein group and a low-protein group found that a 500-kcal calorie deficit resulted in 9.9-11.2% weight loss in both groups. No difference was found between the high protein group (1.6g/kg) and the low protein group (0.8g/kg). However; when only fat mass was measured, the high protein group had lost a much larger amount than the low protein group. (5)

Yet another study conducted for four weeks with a 40% energy-deficient diet concluded that recreationally active overweight men consuming 2.4 g protein/kg body weight/day experienced greater increases in LBM and losses in FM than those consuming a diet containing 1.2 g protein/kg body weight/day when combined with a high volume of resistance exercise. (6)

Proteins preserve lean body mass because amino acids, especially leucine, induce muscle protein synthesis. To certain extent proteins also play a role in satiety and will help you feel full when on a calorie restriction diet.

Recommended Protein Intake

Research suggests that ≥2 g protein/kg body weight/day may be required to maintain LBM during a calorically-deficient diet. (1) This amount is usually too high. The current RDA for all adults for protein is at 0.8g/kg. It is seen that Indian diets are carbohydrate predominant and the amount of proteins consumed do not even reach this RDA.

This poses a problem because one cannot suddenly increase the protein intake for a person who is not used to consuming even the minimum requirements of proteins. If the protein intake is increased at once, it may cause intestinal discomfort and indigestion leading to constipation, diarrhea, etc. The protein intake should therefore be increased gradually. 

 When should protein be supplemented?

Healthy sources of dietary proteins include lean cuts of beef, fish, eggs, legumes, and dairy products like milk, cheese, yogurt, etc. Protein is also present in smaller quantities in starchy foods and vegetables. If these protein sources do not meet the increased requirement while on a calorie deficit, protein supplements can be given to such individuals. 

One of the most popular supplements given to those on a calorie deficit for weight loss is whey protein. Whey protein has a very high biological value which implies readily available amino acids for absorption. (7) Studies on body composition showed that fat-free mass stayed similar for obese adults on adding whey protein supplementation to a four-week long, very low-calorie diet and exercise intervention. (8)

Also, whey protein, enriched in leucine, activates protein synthesis after intake and presents beneficial effects on the preservation of lean body mass in older adults. (7)


Preservation of lean body mass is key when one wants to lose weight. Proteins are vital macronutrients that help in this process. It is equally essential to combine protein intake and calorie deficit with resistance training to preserve the total lean body mass. Current literature shows that total preservation of LBM is not possible with only a dietary intervention and that the combination of exercise and energy intake restriction is generally more effective. (9)

So do not shy away from proteins. Let them be your true companions on your way to fitness mass!

Let us know whether this information was beneficial to you in the comments section below.

Author: Dr Pooja Nilgar (Content writer and editor)


  1. Willoughby, D., Hewlings, S. and Kalman, D., 2018. Body composition changes in weight loss: strategies and supplementation for maintaining lean body mass, a brief review. Nutrients10(12), p.1876.
  2. Tsa, A.G. and Wadden, T.A., 2005. Systemic review: An evaluation of major commercial weight loss program in the United States. Annals of Internal Medicine142(1), pp.56-66.
  3. Ravussin, E., Lillioja, S., Knowler, W.C., Christin, L., Freymond, D., Abbott, W.G., Boyce, V., Howard, B.V., and Bogardus, C., 1988. Reduced rate of energy expenditure as a risk factor for body-weight gain. New England Journal of Medicine318(8), pp.467-472.
  4. Evans, E.M., Mojtahedi, M.C., Thorpe, M.P., Valentine, R.J., Kris-Etherton, P.M. and Layman, D.K., 2012. Effects of protein intake and gender on body composition changes: a randomized clinical weight loss trial. Nutrition & metabolism9(1), pp.1-9.
  5. Mojtahedi, M.C., Thorpe, M.P., Karampinos, D.C., Johnson, C.L., Layman, D.K., Georgiadis, J.G. and Evans, E.M., 2011. The effects of a higher protein intake during energy restriction on changes in body composition and physical function in older women. Journals of Gerontology Series A: Biomedical Sciences and Medical Sciences66(11), pp.1218-1225.
  6. Longland, T.M., Oikawa, S.Y., Mitchell, C.J., Devries, M.C. and Phillips, S.M., 2016. Higher compared with lower dietary protein during an energy deficit combined with intense exercise promotes greater lean mass gain and fat mass loss: a randomized trial. The American journal of clinical nutrition103(3), pp.738-746. 
  7. Boirie, Y. and Guillet, C., 2018. Fast digestive proteins and sarcopenia of aging. Current opinion in clinical nutrition and metabolic care21(1), pp.37-41.
  8. Larsen, A.E., Bibby, B.M. and Hansen, M., 2018. Effect of a whey protein supplement on preservation of fat free mass in overweight and obese individuals on an energy restricted very low caloric diet. Nutrients10(12), p.1918.
  9. Backx, E.M.P., Tieland, M., Borgonjen-Van Den Berg, K.J., Claessen, P.R., Van Loon, L.J.C. and De Groot, L.C.P.G.M., 2016. Protein intake and lean body mass preservation during energy intake restriction in overweight older adults. International journal of obesity, 40(2), pp.299-304.

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