Losing weight with calorie restriction and enough protein consumption
How to lose weight is a question people always ask in modern society, and there are many ways, including exercise or changing eating habits (including the modification of food proportion/composition you consume). Ketogenic diet and low-carbohydrate have been recommended by doctors, dietitians, and books as ways to lose weight. However, whether low-carbohydrate diet or low-fat diet have been debated for a long time, and there is still no conclusion that which one is better; besides, the food composition is not the only factor affecting your body weight, the frequency and the calorie of food intake are also important factors affecting the body shape.
A recent study compared the changes in body composition and metabolic health of mice in response to two energy-restricted diets with low-carbohydrate or low-fat content in the same amount of protein. [1] The mice were fed with a high-fat diet to induce obesity for 18 weeks; after the obesity phase, the mice were randomly assigned to a low-carbohydrate diet or low-fat diet with calorie restriction (CR) for six weeks. The result demonstrated that the mice’s body weight decreased in both diet groups, which means both diets are effective in losing bodyweight under conditions of CR. Besides, both diets had similar effects on glucose tolerance improvement, energy metabolism, and physical activity. The authors concluded that the total energy intake should be targeted for the control of body weight and glucose status, while low-carbohydrate or low-fat diet can be left to personal preference.
It will be more interesting if the authors also compared mice with both CR and wheel running or wheel running only. Theoretically, the mice with both CR and wheel running should lose more weight and have better control of glucose status; however, the comparison between mice with CR only and mice with wheel running only will be the most exciting part in the add-on. I would expect the mice with CR only have lower body weight and better glucose control than the mice with wheel running only. As the saying “you are what you eat,” eating plays an essential role in body weight and glucose status control.
Age is also another factor affecting body weight, body composition, and glucose status. In this study, the authors started CR with mice at 28 weeks old, which is equal to people around 37–38 years old. If the CR starts with mice at 1 year old (~ 58 years old in people) or even older, does CR still have a similar effect on body weight and glucose tolerance?
As we want to lose more fat instead of lean mass, the amount of protein in daily food intake cannot be ignored. The author fixed the protein percentage in 20% in both low-carbohydrate diet and low-fat diet from the same source (casein with the addition of L-cysteine), and they did not observe significant changes of skeletal muscle mass during CR. Besides, high protein consumption could lead to increased retention of lean body mass during CR. [2] Besides, a recent randomized clinical trial revealed that “no difference between low-fat and low-carbohydrate diets in weight loss during a 12-month period, and neither baseline insulin secretion nor genotype pattern relevant to carbohydrate and fat metabolism was associated with the dietary effects on weight change.” [3] That also supports the idea that calorie restriction is a vital factor when you want to lose your weight; when you are doing calorie restriction, enjoy whatever the food you like and remember to get enough protein.
Reference
[1] Minderis P, Fokin A, Dirmontas M, Ratkevicius A. Hypocaloric Low‐Carbohydrate and Low‐Fat Diets with Fixed Protein Lead to Similar Health Outcomes in Obese Mice. Obesity. 2020 Jul 8.
[2] Pasiakos SM, Cao JJ, Margolis LM, Sauter ER, Whigham LD, McClung JP, Rood JC, Carbone JW, Combs Jr GF, Young AJ. Effects of high‐protein diets on fat‐free mass and muscle protein synthesis following weight loss: a randomized controlled trial. The FASEB Journal. 2013 Sep;27(9):3837–47.
[3] Gardner CD, Trepanowski JF, Del Gobbo LC, Hauser ME, Rigdon J, Ioannidis JP, Desai M, King AC. Effect of low-fat vs low-carbohydrate diet on 12-month weight loss in overweight adults and the association with genotype pattern or insulin secretion: the DIETFITS randomized clinical trial. Jama. 2018 Feb 20;319(7):667–79.
