Increasing the amount of protein you eat may help support weight loss by regulating certain hormones and helping you feel fuller longer, among other benefits.
Protein plays a key role in supporting weight management and overall health.
A high protein intake boosts metabolism, reduces appetite, and affects several weight-regulating hormones.
Protein can help you lose weight and belly fat, and it works via several different mechanisms.
This is a detailed review of the effects of protein on weight loss.
Protein changes the levels of several weight-regulating hormones
Your weight is actively regulated by your brain, particularly by an area called the hypothalamus.
To determine when and how much you should eat, your brain processes multiple types of information.
Some of the most important signals to your brain come from hormones that change in response to feeding.
A higher protein intake actually increases your levels of the satiety (appetite-reducing) hormones GLP-1, peptide YY, and cholecystokinin while reducing your levels of the hunger hormone ghrelin.
If you replace some of the carbs and fat in your diet with protein, you may experience less hunger and feel greater satiety.
By modifying the levels of appetite-regulating hormones, protein may reduce your hunger and help you feel fuller longer, meaning you may end up eating fewer calories.
Digesting and metabolizing protein burns calories
After you eat, your body uses some calories to digest and metabolize the food.
This is often called the thermic effect of food.
Although not all sources agree on the exact figures, it is clear that protein has a much greater thermic effect (20 to 30%) than carbs (5 to 10%) or fat (0 to 3%).
A thermic effect of 30% for protein would mean that 100 calories of protein end up as only 70 usable calories.
Protein makes you burn more calories (increases ‘calories out’)
Due to the high thermic effect and a positive effect on resting energy expenditure and maintaining lean muscle, a high protein intake tends to boost metabolism.
It makes you burn more calories around the clock, including during sleep.
A high protein intake has been shown to boost metabolism and increase the number of calories burned.
This effect is particularly pronounced during overfeeding (when you’re eating a calorie surplus). In one small 2015 study, overfeeding with a high protein diet increased calories burned by 260 per day.
Protein reduces appetite and makes you eat fewer calories
Protein can reduce hunger and appetite via several mechanisms.
This can lead to an automatic reduction in calorie intake.
In other words, you end up eating fewer calories without having to count calories or consciously manage portions.
Some older studies have shown that when people increase their protein intake, they start eating fewer calories.
This works on a meal-to-meal basis and as a sustained day-to-day reduction in calorie intake as long as protein intake stays high.
In one 2005 study, consuming 30% of calories from protein caused people to automatically drop their calorie intake by 441 calories per day, which is a significant amount.
So, high protein diets have not only a metabolic advantage but also an appetite advantage, making it much easier to cut calories compared with lower protein diets.
Protein may support weight loss without conscious calorie restriction
Protein works on both sides of the “calories in versus calories out” equation. Eating more protein may make it easier to naturally reduce the number of calories you consume while increasing the number of calories you burn.
For this reason, it’s not surprising that high protein diets lead to weight loss, even without intentional restriction of calories, portions, fat, or carbs.
In one older study of 19 people with overweight, increasing protein intake to 30% of calories caused a massive drop in calorie intake.
In this study, the participants lost an average of 11 pounds over a period of 12 weeks. Keep in mind that they only added protein to their diet — they did not intentionally restrict anything.
Although the results aren’t always this dramatic, most studies do show that high protein diets lead to significant weight loss.
A higher protein intake is also associated with less belly fat, the harmful fat that can build up around your organs and cause disease.
All that being said, losing weight is not the most important factor — keeping it off in the long term is what really counts.
Many people can go on “a diet” and lose weight, but most of them end up gaining the weight back.
Interestingly, a higher protein intake can also help prevent weight regain.
So protein can not only help you lose weight but also help you keep it off in the long term.
Protein helps prevent muscle loss and metabolic slowdown
Weight loss doesn’t always equal fat loss.
When people lose weight, they tend to lose muscle mass as well.
But what you really want to lose is body fat — both subcutaneous fat (under your skin) and visceral fat (around your organs).
Losing muscle is a side effect of weight loss that most people don’t want.
Another side effect of losing weight is that your metabolic rate tends to decrease.
In other words, you end up burning fewer calories than you did before you lost the weight.
This is often referred to as metabolic compensation, and it can amount to several hundred fewer calories burned each day.
Eating plenty of protein can reduce muscle loss, which should help keep your metabolic rate higher as you lose body fat.
Strength training is another major factor that can reduce muscle loss and metabolic slowdown when losing weight.
For this reason, a high protein intake and heavy strength training are two incredibly important components of an effective fat loss plan.
How much protein is optimal?
The DRI (Dietary Reference Intake) for protein is only 46 grams (g) and 56 g for the average woman and man, respectively.
This amount may be enough to prevent deficiency, but it’s far from optimal if you’re trying to lose weight (or gain muscle).
Most studies on protein and weight loss express protein intake as a percentage of calories.
According to these studies, aiming to consume 30% of calories from protein seems to be very effective for weight loss.
For example, 30% of 2,000 calories = 600 calories (0.30 x 2,000). Protein has 4 calories per gram, so 600/4 = 150 calories.
So, in simple terms, if you’re on a 2,000-calorie-per-day diet and you want 30% of those calories to come from protein, you would aim to eat around 150 g of protein per day.
You can also aim for a certain number based on your weight. For example, aiming for 0.7 to 1 g of protein per pound of lean mass (1.5 to 2.2 grams per kilogram) is a common recommendation.
It is best to spread your protein intake throughout the day by eating protein with every meal.
Keep in mind that these numbers don’t need to be exact. Anything in the range of 10 to 35%, which is the acceptable macronutrient distribution range of calories, should be effective.
How to get more protein in your diet
Increasing your protein intake is simple. Just eat more protein-rich foods.
These include:
Meats: chicken, turkey, lean beef, pork, etc.
Fish: salmon, sardines, haddock, trout, etc.
Eggs: all types
Dairy: milk, cheese, yogurt, etc.
Legumes: kidney beans, chickpeas, lentils, etc.
Consider choosing a combination of lean animal-based proteins and plant-based proteins to manage calories and promote heart health by reducing saturated fat intake.
Taking a protein supplement can also be a good idea if you have difficulty reaching your protein goals. Whey protein powder has been shown to have numerous benefits, including increased weight loss.
Even though eating more protein seems simple when you think about it, actually integrating this into your life and nutrition plan can be difficult.
Using a calorie/nutrition tracker in the beginning may be a helpful way to get a handle on your protein intake. One strategy you might consider is weighing and measuring your food in order to make sure you’re hitting your protein targets.
You don’t need to do this forever, but it’s very important in the beginning until you get a good idea of what a high protein diet looks like.
Frequently asked questions
How much protein should I eat a day to lose weight?
The Food and Drug Administration (FDA) suggests that most U.S. adults need around 50 grams (g) of protein daily.
However, this is far from optimal if you’re trying to lose weight.
To determine your daily protein intake for weight loss, aim for 30% of your total calorie intake or 0.7 to 1 g of protein per pound of body weight.
Does protein help you lose belly fat?
Yes — according to a 2021 study, a high protein intake is associated with less belly fat (the harmful fat that can build up around your organs and cause disease).
But this study was focused on older men and may not necessarily apply to all populations. More research is needed on this topic.
Does eating protein help lose weight?
Yes, eating protein can help you lose weight and belly fat. A high protein intake boosts metabolism, reduces appetite, and changes levels of several weight-regulating hormones.
Protein is the easiest, simplest, and most delicious way to lose weight
When it comes to fat loss, weight management, and overall health, protein is the king of nutrients.
You don’t need to restrict anything to benefit from a higher protein intake. It’s all about adding to your diet.
This is particularly appealing because most high protein foods also taste really good. Eating more of them is easy and satisfying.
A high protein diet can also be an effective obesity prevention strategy — not something that you just use temporarily to lose fat.
By permanently increasing your protein intake, you tip the “calories in versus calories out” balance in your favor.
Over months, years, or decades, the difference in your waistline could be huge.
However, keep in mind that calories still count. Protein can reduce hunger and boost metabolism, but you won’t lose weight if you don’t eat fewer calories than you burn.
It is definitely possible to overeat and negate the calorie deficit caused by the higher protein intake, especially if you eat a lot of highly processed foods.
For this reason, you should still base your diet mostly on nutrient-rich foods such as fruits, vegetables, beans, lean meat, and whole grains.
Although this article focused only on weight loss, protein also has numerous other benefits for health.