How quickly you see physical changes from increasing your protein intake depends on many factors, such as age, sex, activity level, body size and composition, and genetics. Studies show that high-protein diets effectively spur weight loss within 6 to 12 months, with the most dramatic results happening within the first few weeks.

Effects of High-Protein Diets on Weight and Body Composition

Several studies found that high-protein diets effectively manage weight and support muscle regeneration and development. Here’s what researchers found:

  • Weight loss: Across multiple studies, researchers found that diets that included more than the recommended daily amount of protein induced weight loss and prevented obesity (excess body fat levels).
  • Increasing muscle and lean body mass: When combined with resistance training, high-protein diets lead to gains in lean body mass (the weight of your body minus fat) and muscle strength.
  • In adults with metabolic syndrome: High-protein diets resulted in more weight loss in people with metabolic syndrome than diets that included the standard recommended amounts.
  • Preventing weight regain: One review found some evidence that a high-protein diet prevented people from regaining the weight they lost.

What’s Considered “High Protein”?

Any diet that recommends more than the daily recommended amounts of protein is “high-protein.” Currently, researchers define it as getting over 35% of your daily energy (calories) from meat or other protein sources.

Health authorities in the United States recommend that adults eat 0.8 grams (g) of protein per kilogram (kg) (about 2.2 pounds) of bodyweight a day. Still, there’s controversy, and researchers note this represents the amount you need to avoid malnutrition and muscle loss.

How much protein you need depends on your health status, sex, goals, levels of activity, and age. In most studies, high-protein diets between 1 and 2 g per kg (2.2 to 4.4 g per pound) effectively contributed to weight loss and body composition goals.

Before starting, talk to your healthcare provider about the benefits and risks of adopting a high-protein diet.

How High-Protein Diets Work

There are several mechanisms for how high-protein diets spur weight loss and change body composition. These include:

  • Fullness: Eating protein causes the release of hormones, such as GLP-1, CCK, and PYY, which increases your “satiety:” how full you feel afterward. As a result, a high-protein diet reduces how much you eat overall, leading to weight loss.
  • Appetite hormones: Researchers found that increasing protein intake reduces levels of the hunger hormone, ghrelin. Lower levels in the blood reduce appetite, which can spur weight loss.
  • Metabolism: High-protein diets can also raise metabolism, which is how your body uses energy. Researchers found they increased basal metabolic rate (energy used for essential life functions) and resting metabolic rate (energy used at rest), resulting in a greater calorie burn.
  • Thermic effect: The “thermic effect” is the energy it takes to break down food. Protein has a higher thermic effect than other foods, requiring 20 to 30% of the calories you get from it to break it down for energy. As a result, your body burns more calories.
  • Ketogenesis: Triggered by starvation, exercise, or diet, ketogenesis is an alternative form of energy production. The liver produces ketone bodies by breaking down fat and amino acids, which the body uses for energy. This increases satiety and can trigger rapid weight loss.  

Risks of a High-Protein Diet

Generally, high-protein diets are safe for most people and pose few health risks. However, there may be health risks, including:

  • Kidney damage: If you’ve been diagnosed with kidney disease, your healthcare provider may recommend a low-protein diet, as protein can worsen it.
  • Kidney stones: One study found that eating higher levels of animal proteins raised the risk of kidney stones. The same study found that dairy protein sources protect against this effect.
  • Disease risk: High-protein diets can be rich in red meat and saturated fat (an unhealthy fat that’s solid at room temperature), which raises the risk of heart disease and colon cancer.    

Key Takeaways

  • High-protein diets are effective in spurring weight loss and improving body composition.
  • This is because of effects on metabolism, appetite, and your body’s energy use.
  • High-protein diets may not be safe if you have kidney disease and may raise cancer and heart disease risk.

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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Mark Gurarie

By Mark Gurarie

Gurarie is a writer and editor. He is a writing composition adjunct lecturer at George Washington University. 

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