Why Protein Matters for Weight Loss: The Science Explained
Weight Loss

Why Protein Matters for Weight Loss: The Science Explained

#1 Low Carb & Keto Diet App Since 2010

Track macros, calories, and access top Keto recipes.

Download on the App Store
Get in on Google Play

Why Protein Matters for Weight Loss: The Science Explained

Posted 8 months ago

Brian Stanton

Brian Stanton


When researchers analyzed dozens of clinical trials from the past few decades, they found something interesting: people who ate more protein lost more weight, maintained more muscle, and were less likely to experience weight rebound.[*] Protein seemed to be a magic macro for shedding fat

But the effects of a high-protein weight loss diet aren't magical. Instead, they're rooted in the mechanics of satiety, metabolism, and energy balance. 

We'll cover these mechanics (and practical tips on getting enough protein for weight loss) shortly. First, though, let's discuss the “secret” to losing weight. 

The "Secret" To Weight Loss

The secret to weight loss isn't a diet, macro ratio, or exercise protocol. Minding your macros (like protein) and exercising can help you lose weight, but they aren't fundamental to the process. 

The fundamental concept—or "secret" to weight loss— is energy balance. The principle is simple: if you consume less energy than your metabolism burns through rest and movement, you'll lose weight.[*

The converse is also true. If you consume more calories than you burn, you'll gain weight. 

Is protein good for weight loss? Yes. High protein and Keto diets curb hunger while increasing metabolic burn but don't guarantee weight loss.[*][*] You can overeat on any diet—pass the cashews, Thelma!—even if the diet is comprised entirely of healthy foods. 

It's easier, however, to overeat high-carb refined foods than protein-rich whole foods. Refined carbs (especially sugar) hack your reward system, so you keep craving them even after consuming a boatload of calories.[*

How Protein Helps With Weight Loss

Now that we've covered the fundamentals of weight loss, let's apply that logic to high-protein diets. Here are some mechanisms by which protein keeps your energy intake below your energy burn. 

#1: Hunger hormones

Researchers have long known that high-protein foods are filling.[*] Protein promotes satiety by:

  1. Reducing levels of ghrelin, the primary hunger hormone
  2. Increasing fullness hormones like glucagon-like-peptide-1, cholecystokinin, and peptide tyrosine-tyrosine

Next time you feel satisfied after a nice piece of fish, lean in and purr to your partner: Honey, my peptide tyrosine-tyrosine is kicking in. Then briskly change the subject. 

#2: Increased energy burn

Protein demands more energy to metabolize than fat or carbs.[*] This increased energy burn cycles back to boost satiety. Protein also increases resting energy expenditure by preserving lean mass—a good combo for energy balance. 

#3: Slower gastric emptying

After eating a high-protein meal, your stomach takes longer to empty. This promotes fullness and reduces blood sugar spikes, which helps curb subsequent snacking. 

#4: Ketones

Reducing carbs on a high-protein, low-carb diet produces more of a satiety-promoting ketone called beta-hydroxybutyrate. The key to this benefit is keeping protein high and carbs low. 

The Evidence for High-Protein Weight Loss Diets

Shifting gears for a moment, let's review some literature on protein for weight loss:

  • A 2012 meta-analysis of 24 randomized controlled trials found that high-protein diets (27–35% of energy intake) led to 1.7 pounds more weight loss than standard protein diets (16–21% of energy intake.)[*]
  • A 2012 meta-analysis of 74 randomized controlled trials found that high-protein diets (16–45% of energy intake) led to 0.8 pounds more weight loss than standard protein diets (5–23% of energy intake.)[*]
  • A 2004 randomized controlled trial found that a 20% higher protein intake during weight maintenance led to 50% less weight regain after three months.[*]

The takeaway is that the protein's weight loss effects aren't always massive but aren't insignificant either. 

How Much Protein Should You Consume for Weight Loss?

The required daily allowance (RDA) for protein is 0.8 grams per kilogram of body weight. That's about 73 grams of protein (292 calories) for a 200-pound person and wouldn't qualify as "high-protein" in the weight loss studies we just covered.  

Skip the RDA. Remember, it’s more of a minimum requirement. For weight loss, muscle maintenance, and general health, we recommend you shoot for at least 25% of your daily calories from protein. 

If you're on a 2000-calorie diet, 25% is 500 calories. Your daily protein target would be 125 grams.

Even if you're happy with your weight, do it for your muscles. The research suggests that very active people should consume more than double the RDA to meet their needs.[*] (This recommendation is also in line with protein targets for weight loss.[*]) 

Don't stress too much about timing your protein intake. Consuming the protein within a few hours of exercise will supply the necessary amino acids (like leucine) to promote muscle synthesis.[*

How To Get More Protein Into Your Diet

Getting at least 25% of your calories from protein requires a conscious effort. It requires making protein the centerpiece of every meal. 

Start with your protein target and build the rest of your diet accordingly. Always ask: "How can I consume 30–40 grams of protein with this meal?"

Great protein sources include meat, fish, organ meats, eggs, and whey protein. If you're vegan or vegetarian, use a plant-based protein powder to hit your target. 

Also, cramming 150 grams of protein into one meal—two sirloin steaks, please!—isn't the same as spreading it throughout the day. You can only absorb about 0.4 grams per kilogram of body weight (about 36 grams for a 200-pound person) at once.[*] So, in that sense, protein timing does matter, but not in the way most people mean. 

Tracking Your Protein Intake

The simplest way to track protein intake is to log your meals with Carb Manager. You input your foods—type them, say them, or snap a pic of lunch—and the app does the rest. 

Beyond tracking, you can also set protein targets within the app. That's where the real magic happens. 

Having a target (and tracking progress toward that target) creates accountability and motivation. And when you're motivated and accountable, you're more likely to get results. 

Comments 2

  • RousingKale376068

    RousingKale376068 7 months ago

    When we enter a food where in the app does it show the amount of calories from each macro source ie from fat, protein or carbs?

    • FortuitousRadish859647

      FortuitousRadish859647 2 months ago

      It doesn't show the calories from each macro in the app, but you can manually calculate it by multiplying carbs and protein by 4 and fat by 9 calories per gram.