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Why Protein is KING for Weight Loss

First, when you are trying to lose weight, calories in and calories out is the #1 rule! So what is the next important factor to weight loss? Yep, you guessed it, PROTEIN!

Decades of scientific research on nutrition and weight loss has uncovered three key factors:

  • First, exercise is important, but calories consumed and calories burned matters more for weight loss than the hours spent in the gym.

  • Second, there is no single best weight loss plan for everyone. Lots of diets can work really well as long as total calorie balance is in a deficit.

  • Third, protein is the key “lever” in your diet to increase the likelihood of your ability to lose weight and sustain long term weight loss.

What I want you to get out of this article:

  1. What is protein and why do we need it?

  2. How much protein do you need per day to help you lose weight?

  3. What are the benefits of protein and what you need to consider when planning your nutrition.


Protein is an important macronutrient that is involved in nearly all bodily functions and processes. It plays a key role in exercise recovery and is an essential dietary nutrient for healthy living. The elements carbon, hydrogen, oxygen, and nitrogen combine to form amino acids, the building blocks of protein. Protein and amino acids are primarily used to create bodily tissues, form enzymes and cellular transporters, maintain fluid balance, and more. I know this is a lot of biochemistry but bear with me to get to usable information.

Dietary protein is broken down into amino acids which are then absorbed from the GI tract into the bloodstream. Dietary protein, and protein from the body contribute to the overall amino acid pool. About 50% of dietary protein makes it into the blood stream, and only 10% goes to new protein(tissue) synthesis. That isn’t very much, so now you are starting to see why protein is so important.


If you want to lose weight, aim for a daily protein intake between .73 and 1 gram per pound of body weight (1.6 and 2.2 grams of protein/kg). Athletes and heavy exercisers should consume 1-1.5 grams per pound of body weight (2.2-3.4 grams of protein/kg) if aiming for weight loss.

40 grams of protein post workout is most likely the best “bang for your buck” in terms of the most muscle growth in adults.

Application: Resistance training and protein are both critical to muscle growth.

To promote muscle growth, consume about 30g of protein and carbs within 2 hours post exercise. Meals should be spaced out 3-5 hours apart to optimize digestion and absorption. Consuming protein within 1-3 hours before bed can prevent overnight reduction in muscle protein synthesis(it will help you grow muscle but be careful of the calories).


While there are many benefits of dietary protein, there are four main areas that have direct effects on weight loss:

  1. Satiety

  2. Lean mass

  3. Thermic effect of food

  4. Storage as body fat

Let us take a deeper dive into each of these topics.


One of, if not the biggest factor that impedes weight loss is hunger.

People are far less likely to stick with a nutrition or diet plan if they experience high levels of hunger, especially if they are hungry for long periods of time. That is where protein comes’s the most satisfying of all the macronutrients. In fact, high protein snacks can be an effective strategy as part of a weight loss plan.

This works because high protein snacks allow you to go longer between eating and also eat less at subsequent meals. Studies have shown that including protein and a glass of water decreases hunger compared to water alone.

The exact amount of protein you need on a daily basis to help curb hunger is up for debate but a safe number is 1g/lb of body weight.


The illusive body recomposition (preserving or even gaining lean body mass during periods of caloric restriction) can only happen in the presence of protein. One study compared the effect of low protein intake (1.0 grams per kilogram per day) to high protein intake (2.3 g/kg per day) on lean body mass over a short term caloric deficit. On average, the low protein group lost about 1.6 kilograms (3.5 pounds) of muscle mass while the high protein group only lost 0.3 kg (0.66 pounds) of muscle mass (6).

Currently, most evidence suggests that .73g of protein/lb of body weight is recommended for a daily target to spare lean body mass (muscle) during periods of weight loss. Quality of the protein matters and complete proteins (animals) are digested and assimilated better than incomplete proteins (plants). To put it simply, if you are on a diet (calorie deficit) you need more protein so you don’t lose muscle.


The thermic effect of food is the “cost” of digesting your food. It’s how much energy it takes your body to break down, assimilate and absorb the nutrients from your food.

Essentially, it takes some energy to break food down, digest it, and turn it into energy. Protein has the highest “cost” of all the three macronutrients.

While the total effect that the thermic effect of food has on daily energy expenditure and weight loss is not very significant, lt’s worth knowing in regards to weight loss.

In one study, a high protein diet increased the thermic effect of food by roughly 6-8 kcals per hour when compared to a low protein diet, which may translate to ~50-75 calories per day (8). That’s 6-7 chocolate chips!


The body processes the three different macronutrients (i.e. proteins, carbohydrates, and fats) in very different ways. When you are trying to figure out how many calories you need on a daily basis to lose weight (i.e.- be in a calorie deficit) and you eat more protein than you need, it’s difficult for your body to store it as body fat. So a high protein diet is helpful to keep you from gaining fat when you overeat. Now don’t get me wrong you can still store protein as body fat, it’s just a harder biochemical process for your body to turn protein into body fat.

Studies have shown that protein can only be stored as body fat with roughly 66% efficiency, while carbohydrates store with 80% efficiency and fats store at 96% efficiency (9).

In summary, during weight loss, overeating protein results in much less stored body fat than overeating carbohydrates or fat.


Nutritional Guidelines suggest a daily intake of .73 and 1 g/lb of body weight (1.6-2.2 g/kg) to lose weight. Athletes and heavy exercisers should consume 1-1.5 g/lb of body weight (2.2-3.4 g/kg) if aiming for weight loss.

There are lots of strategies to lose weight and depending on your goals, body composition, and dieting history, while many different diets can be effective, the protein content of a diet is an important factor to losing weight. Protein has been shown to promote satiety, help maintain lean body mass, slightly increase the thermic effect of food, and can reduce how efficient the body is at storing extra calories as body fat.

Two points to apply to your own nutrition plan:

  1. The timing of your protein isn’t nearly as important as your total daily protein when you are in a calorie deficit.

  2. Resistance training is critical during periods of high protein intake and being in a calorie deficit. This signals your body to do something with the protein by turning it into muscle.

Eat Well, Live Well


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