Protein Content and Glycemic Index: Role in Weight Control and Maintenance

With the turn of the century, India has witnessed a rapid epidemiological shift in disease prevalence from communicable to non-communicable, mostly due to rise in obesity.1 With a high predisposition to abdominal obesity and accumulation of visceral fat, termed as “Asian Indian phenotype,”2 the prevalence of obesity increased significantly from 9.8% in 2006 to 11.7% in 2009 in India.3 The sudden rise in obesity is not only leading to various metabolic diseases such as diabetes, hypertension, and heart ailments but is now also being considered as a disease entity in itself by American Medical Association.4

Considering the mounting disease burden in the country, there is a pressing need to raise awareness about the importance of maintaining a healthy body weight and finding ways to counter the rising prevalence of obesity.

In this regard, bringing behavioural and lifestyle changes, such as self-monitoring, accountability, motivational interviewing, frequent self-weighing, regular physical activity, and bringing dietary modifications are the most common interventions for the weight loss.5

Due to its role in achieving and managing ideal body weight, protein is increasingly getting recognized as an important tool to prevent or treat obesity.6 Although when it comes to the exact amount of protein required to lose weight, there remains ambiguity. While as a rule of thumb, a healthy individual requires 0.8 gram (g) of protein per kilogram (kg) ideal body weight (IBW),6 which roughly makes for 15% to 20% of the calorie of a day’s diet7 to lose weight, however, evidence suggests that increasing the intake can be helpful in weight management.8

Role of high protein diet in weight management- Rationale and Mechanism

Until sometimes back mostly studies backed the notion that it is not just one macronutrient which is crucial to weight loss, but cutting down on calories, irrespective of the macronutrient, which also leads to a sustained and clinically meaningful weight loss.9 However, several recent studies also indicate that reducing fat and carbohydrates intake, in fact, is a more effective strategy in creating a calorie deficit of 500 to 1000 kcal/day and should result in a weight loss of 1 to 2 pounds per week.5

This is because of difference in the energy these macronutrients yield and the level of satiety they help in achieving. While 1 g of protein gives 4 kcal of energy, which is exactly same as the amount of energy generated by 1 g of carbohydrate, when it comes to satiety, protein is considered a better option, even when compared to complex carbohydrate. As far as fats are concerned, despite aiding in satiety, they are never a good choice in weight management because of their high calorific value, which is 9 kcal/g.

Collective data from several studies indicate that higher-protein diets that contain between 1.2 and 1.6 g protein per kg IBW, spread across the day in amounts of 25 to 30 g/meal, help provide improvements in appetite, body weight management, and cardiometabolic risk factors.6

Protein is considered to be the most important nutrient in weight loss and management.10  Proteins are more satiating as compared to carbohydrates and fats.10,11   Whey protein offers greater satiety than casein or soy.11

Protein helps in suppressing hunger by following ways:12,13

  • increases amino acids concentration which in turn triggers release of satiety promoting hormones in the body;
  • increases thermogenesis;
  • elevated level of amino acids is detected by satiety centre in the brain; and
  • releases bioactive peptide during protein digestion

Role of low glycemic index (GI) diet in weight loss

The role of low GI foods is yet to be understood in terms of weight management and hunger control.6 While some scientists strongly support low-GI foods as the ultimate solution to the obesity problem, the logical challenges that people face in predicting GI in commonly cooked foods make it difficult not only to sustain compliance in long term but also to make recommendations by experts for weight management.14

However, as their role is getting more defined in weight management, more experts bat for them as an important strategy in weight loss. Due to the slower rates at which low GI foods are digested and absorbed in the body and their corresponding effects on postprandial glycemia and hyperinsulinemia, they help in weight control in two ways, first by promoting satiety and second by promoting fat oxidation at the expense of carbohydrate oxidation.15 In fact, even in the foods with comparable appearance and nutrient content, foods with low-GI induce higher satiety than their high-GI counterparts and are followed by less energy intake at subsequent meals.15

This clearly indicates that long-term inclusion of low GI foods in the diet can lead to a significant weight control and maintenance.

Dietary requirements during weight management

An imbalance between calories intake and the amount of energy used in terms of daily physical activity is generally accepted as one of the most important reasons responsible for obesity.6 Obesity thus is touted majorly as a nutrition-related problem.14 Therefore, apart from burning or utilizing more calories than consumed in the form of physical activity, dietary modification remains a key strategy in weight management.

As stated above, due to the role of protein in appetite, alterations in energy metabolism and calorie intake, a diet low in carbohydrate and fat and high in protein is considered as the most scientifically validated dietary modification/requirement for an effective weight management.

While bringing dietary modifications, keeping the source of macronutrients in mind, especially fats and carbohydrates, is equally important. According to recommendations, to achieve the goals of weight management, the intake of dietary fat should not exceed more than 25–35% of the total energy ingested and with an aim to reduce the consumption of saturated fat.20 The recommended intake of fat should ideally come from omega 3 and omega 6 fatty acids (polyunsaturated fatty acid [PUFA]), and mono-unsaturated fatty acid (MUFA).20

Same is the case with carbohydrate, reducing simple carbohydrates and increasing complex carbohydrate is known to help in weight management.16 The key to this lies in the difference in their GI. Complex carbs, which are difficult to digest, have low GI, which decreases hunger and increases satiety levels, while simple carbs, which easily and readily get digested to release glucose quickly in the blood to release energy, increase hunger, and reduce satiety.17

Dietary plan / guideline Dietary recommendations
Mediterranean diet Moderate consumption of total fat (especially MUFA) and high consumption of starchy food.12
Atkins diet 3% to 10% of total daily energy intake while fat and protein to be consumed to satisfaction.18
AHA Diet for weight reduction should include fruits, vegetables, whole-grain products, and legumes whereas saturated fat and cholesterol should be restricted.19

 

Consumption of saturated fat to be ˂10% of energy and cholesterol to be ˂300 mg/day.19

Dietary Guidelines for Americans Consumption of macronutrients should be as per age:

Carbohydrate: 45% to 65% (for all age group)

Fat: 30% to 40% (children aged 1 to 3 years) and 20% to 35% (children aged above 3 years and adults)

Protein: 5% to 20%(children aged 1 to 3 years) and 10% to 35% (children aged above 3 years and adults)20

MUFA: mono-unsaturated fatty acid; AHA: American Heart Association

Conclusion

A clinically effective weight management is highly reliant on bringing and sustaining behavioural changes in terms of increasing physical activity to utilize more calories than consumed, and dietary modification. Focussing on the relative dietary content of protein, carbohydrate, fat, types of fat, and their GI are crucial in achieving long-term dietary goals for effective weight management.

References

1Quigley MA. Commentary: shifting burden of disease—epidemiological transition in India. Int J Epidemiol. 2006;35(6):1530-31.

2Pradeepa R, Anjana RM, Joshi SR, Bhansali A, Deepa M, Joshi PR, et al. Prevalence of generalized & abdominal obesity in urban & rural India—the ICMR-INDIAB Study (Phase-I) [ICMR – INDIAB-3]. Indian J Med Res. 2015;142(2):139–50.

3Gupta DK, Shah P, Misra A, Bharadwaj S, Gulati S, Gupta N, et al. Secular trends in prevalence of overweight and obesity from 2006 to 2009 in Urban Asian Indian adolescents aged 14-17 Years. PLoS One. 2011;6(2):e17221.

4Hebebrand J, Holm JC, Woodward E, Baker JL, Blaak E, Durrer Schutz D, et al. A proposal of the European Association for the Study of Obesity to improve the ICD-11 diagnostic criteria for obesity based on the three dimensions etiology, degree of adiposity and health risk. Obes Facts. 2017;10(4):284-307.

5Champagne CM, Broyles ST, Moran LD, Cash KC, Levy EJ, Lin PH, et al. Dietary intakes associated with successful weight loss and maintenance during the weight loss maintenance trial. J Am Diet Assoc. 2011;111(12):1826-35.

6Leidy HJ, Clifton PM, Astrup A, Wycherley TP, Westerterp-Plantenga MS, Luscombe-Marsh ND, et al. The role of protein in weight loss and maintenance. Am J Clin Nutr. 2015;101(Suppl):1320S–9S.

7Pesta DH, Samuel VT. A high-protein diet for reducing body fat: mechanisms and possible caveats. Nutr Metab. 2014;11(1):53.

8Paddon-Jones D, Westman E, Mattes RD, Wolfe RR, Astrup A, Westerterp-Plantenga M. Protein, weight management, and satiety. Am J Clin Nutr. 2008;87(5):1558S-61S.

9Sacks FM, Bray GA, Carey VJ, Smith SR, Ryan DH, Anton SD, et al. Comparison of weight-loss diets with different compositions of fat, protein, and carbohydrates. N Engl J Med. 2009;360(9):859-73.

10Davoodi SH, Shahbazi R, Esmaeili S, Sohrabvandi S, Mohamamd Mortazavian A, Jazayeri S, et al. Health-related aspects of milk proteins. Iran J Pharm Res. 2016;15(3):573-91.

11Veldhorst MAB, Nieuwenhuizen AG, Hochstenbach-Waelen A, van Vught AJAH, Westerterp KR, Engelen MPKJ, et al. Dose-dependent satiating effect of whey relative to casein or soy. Physiol Behav. 2009;96(4):675-82.

12Andersson A and Bryngelsson S. Towards a healthy diet: from nutrition recommendations to dietary advice. Scand J Food Nutr. 2007; 51(1):31-40.

13Chung Chun Lam SMS, Moughan PJ. Whey protein and satiety: implications for diet and behaviour. In: Preedy VR, Watson RR, Martin CR, editors. Handbook of behavior, food and nutrition. Vol 1. New York: Springer; 2011. p. 1107-24.

14Saris WH, Foster GD. Simple carbohydrates and obesity: fact, fiction and future. Int J Obes. 2006;30:S1-S3.

15Brand-Miller JC, Holt SH, Pawlak DB, McMillan J. Glycemic index and obesity. Am J Clin Nutr. 2002;76(1):281S-5S.

16Aller EE, Abete I, Astrup A, Martinez JA, van Baak MA. Starches, sugars and obesity. Nutrients. 2011;3(3):341-69.

17Bornet FR, Jardy-Gennetier AE, Jacquet N, Stowell J. Glycaemic response to foods: impact on satiety and long-term weight regulation. Appetite. 2007;49(3):535-53.

18Strychar I. Diet in the management of weight loss. CMAJ 2006;174(1):56-63.

19Krauss RM, Eckel RH, Howard B, Appel LJ, Daniels SR, Deckelbaum RJ,  et al. AHA Dietary Guidelines: Revision 2000: A Statement for Healthcare Professionals From the Nutrition Committee of the American Heart Association. Circulation. 2000;102:2284-99.

20U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2010. 7th ed., Washington, DC: U.S. Government Printing Office, December 2010.

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