Protein: “Belly Fat” Trap or Key to Body Recomp?

How much protein is really too much? We’ve been seeing a lot of articles popping up in our feeds about the relationship between protein and unwanted weight gain. While most of these articles don’t suggest anything entirely wrong, the information presented is consistently misleading. These articles focus on the caloric intake associated with addition of protein to a diet, rather than the approach of shifting the macronutrient breakdown of the diet. Any caloric increase over expenditure could lead to weight gain. That weight gain might be in your belly. However, a “calorie is a calorie” remains a common fallacy, and added protein does not necessarily lead to weight gain. In fact, it could help you build lean mass and lose fat.

With all of the misinformation floating around, we decided to take some time to break it down - how much protein really is too much? Do we really need to eat that much? One thing to keep in mind when it comes to sports and nutrition science are the challenges associated with these broad studies with potentially limited sample sizes in the nutrition and sports sciences due to practical limitations in engaging relevant populations.

The Basics

We understand protein as one of the three macronutrients, or macros, that are vital to our diets and bodily functions. However, protein isn’t just protein; it is assembled from building blocks called amino acids. Nine of these are essential for making new proteins, but they also have other critical roles in our metabolism. Leucine stands out for those working to build lean muscle because it activates a biological pathway called mTORC1, which triggers muscle protein synthesis (MPS). The availability and concentration of leucine is crucial for this pathway to function effectively.

Historically, dietary advice has focused on a bare minimum recommended daily allowance (RDA) of only 0.8 grams of protein per kilogram of body weight, or 0.36 grams per pound. Most people, even vegetarians, have no trouble meeting this goal. For example, one cup of cooked lentils and one serving of greek yogurt is about 50g of protein. The RDA, however, does not factor in nutrients required as signals for biological processes like mTORC1, and does not take into account benefits of increasing protein intake to accelerate protein-muscle synthesis or meet calorie goals less painfully.

Protein and Weight Loss

Increasingly, studies have shown that increasing the proportion of calories consumed from protein helps maintain satiety and makes it easier to maintain a caloric deficit needed for body recomposition. Research actually shows that ingesting protein and calcium together stimulates production of GLP-1, the peptide hormone produced by intestinal cells, associated with feelings of hunger and satiation.

This, combined with the higher thermic effect of food has resulted in a small but significant increase in loss of fat and a higher percentage of lean mass across randomized controlled trials.¹ So, if you’re trying to lose fat and build muscle, a higher proportion of calories from protein will undoubtedly help, but it won’t do the work for you. Eating a high proportion of protein should also be accompanied by resistance training and, potentially, an energy deficit, depending on personal goals.

What does this mean for someone trying to lose weight or body fat percentage? We like to focus on starting with a caloric budget, setting a protein goal commensurate with lean mass gain objectives (likely 2-3g of protein/kg of body weight), and prioritize getting enough protein to hit that goal. The rest of the calories can be allocated to fat and carbohydrates based on personal preferences and needs. Check out our post on making a lean steak or our post on how we get more protein in our diets for ideas on how to load up on protein calories. However, if you’re trying to build muscle, adding protein, even with additional calories, has shown to result in gains in lean mass, as opposed to fat².

Your Muscle-Building Engine

Optimizing protein intake requires not only consideration for the expanded roles of amino acids, but an individual’s metabolism and fitness goals as well. As we age, for example, our bodies become less efficient at MPS in response to protein intake, contributing to muscle mass decline. Fortunately, research indicates that muscle mass loss is not an inevitability of aging and can be prevented by increasing protein intake to provide a certain threshold value of leucine. Think of mTORC1 as an engine that drives the production of new muscle fibers and leucine as the specialized fuel for the engine. As we age, the engine requires more fuel to simply get started but, once started, can just as effectively synthesize new muscle fibers.

Resistance training acts as an additional signal to the mTORC1 pathway, akin to a powerful booster that optimizes the engine’s performance. While leucine provides the consistent and necessary fuel for activation, resistance training enhances its efficiency and response. The synergistic effects of leucine intake and resistance training maximizes the incremental activation of mTORC1, resulting in optimal muscle growth and repair.

Does Timing Protein Matter?

After a meal, MPS continues for two to three hours and has been found to be most responsive after a fasting period, meaning consuming a protein-rich breakfast should be a priority. In one weight loss study, participants who shifted their daily protein intake from dinner to earlier meals while maintaining the same net daily protein intake lost more weight and more body fat. This is akin to about 20–30 grams of high-quality protein (e.g., whey protein isolate) early in the day to help stimulate MPS.³

Consuming this protein dose after a workout within a two-hour period is crucial for robust increases in MPS. Spacing your protein intake evenly throughout the day also positively impacts MPS rates. Think of it like jumpstarting the engine and then continually fueling it to maintain output.

Evidence does support potential benefits of consuming about 20–40 grams of protein every three to four hours over a 12-hour period, with the first meal within an hour of waking and the last within three hours of going to sleep, however, we have also seen studies that show the timing to total protein amounts is less important than the total amount.⁴ However, we have found logistically that packing that first meal of the day with at least 30g of protein helps get enough throughout the day in addition to the potential added benefits of increased MPS.

Can You Have Too Much?

Evidence does show that high protein intake is associated with renal failure in individuals with a preexisting kidney condition, and it is important to pay attention to cholesterol levels while increasing consumption of meat, especially red meat, as some studies have shown high protein diets can be associated with heart disease. However, there is no conclusive evidence to show that a low fat, high protein diet has any adverse effects in healthy individuals. ⁵

The biggest challenge in increasing protein intake is finding the right mix of foods to fulfill the targeted macronutrient balance: lean meat supplemented with both whey and soy protein can be complemented with high protein grains and legumes. Variety in the diet is important both from a nutritional and psychological standpoint.

The Takeaways

• Try to get 30 grams of high-quality protein at breakfast - this is particularly important for older adults who require this threshold value of leucine to trigger MPS and counteract age-related declines in muscle mass.
• To further optimize protein intake for MPS try to evenly space protein meals (20–40 grams each) every three to four hours to maintain MPS rates throughout the day.⁶
• For weight loss, focus on your total caloric intake first, then hitting your protein goal, and allocate the rest of the calories appropriately. Extra protein can help put on lean mass, but you have to watch your energy balance from total calories.

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