From the Guidelines
For weight loss, the type of protein is less important than ensuring a balanced diet with adequate protein intake, as high-protein diets without caloric restriction do not result in sustained weight loss or improved health 1. When considering protein for weight loss, it's essential to focus on the overall dietary approach rather than the specific type of protein. The American Heart Association recommends that total protein intake should not be excessive, averaging 50 to 100 g/d, and should be reasonably proportional to carbohydrate and fat intake 1.
Key points to consider for weight loss include:
- Ensuring a balanced diet that allows for caloric deficits of 500 kcal/d for each 1 lb lost per week
- Providing a minimum of 1200 kcal/d for women and 1500 kcal/d for men
- Total energy deficit has the greatest overall impact on weight reduction, especially when coupled with increased physical activity and behavior modification to maintain negative energy balance
- Diet composition should be consistent with a balanced eating plan that supports weight maintenance and lowers chronic disease risk
Recent guidelines suggest that higher-protein approaches (25% to 30% of energy) as part of a comprehensive weight loss intervention result in weight loss equivalent to that achieved with a typical protein diet (15% of total calories) when both diets are calorie restricted (500- to 750-kcal/d deficit) 1. However, the most critical factor for successful weight loss is a nutritionally adequate diet that allows for caloric deficits, tailored according to individual food preferences, rather than the specific type of protein consumed 1.
From the Research
Types of Protein for Weight Loss
- There is evidence to suggest that a high proportion of calories from protein can increase weight loss and prevent weight regain 2.
- Different types of proteins, such as casein and whey, may have different effects on satiety and metabolism, with whey being more satiating in the short term and casein being more satiating in the long term 2.
- However, there is no clear evidence that one protein source is superior to others for weight loss, and factors such as amino acid composition, rate of absorption, and protein/food texture may be more important for protein-stimulated metabolic effects 2.
Protein Supplementation and Weight Loss
- Protein supplementation, particularly with leucine-rich whey protein, may help mitigate the adverse effects of weight loss on muscle mass 3.
- However, a study found that whey protein supplementation during diet-induced weight loss did not have clinically important therapeutic effects on muscle mass or strength in middle-aged postmenopausal women with obesity 3.
- A systematic review and meta-analysis found that increased protein intake can help prevent muscle mass decline in adults with overweight or obesity who are aiming for weight loss, with an intake exceeding 1.3 g/kg/day being more effective 4.
Protein and Satiety
- Protein has been shown to induce satiety and reduce energy intake, with high-protein diets being effective for weight loss and weight maintenance 5, 6.
- Different proteins can cause different nutrient-related responses of (an)orexigenic hormones, with protein-induced satiety being related to protein-induced energy expenditure 6.
- However, chronic ingestion of large amounts of sulphur-containing amino acids may have adverse effects on kidney function and blood pressure, particularly in susceptible groups such as individuals with obesity, metabolic syndrome, and diabetes mellitus II 5, 6.