You’ve decided you want to lose some weight, but are not sure how you want to get started. You remember talking to a friend recently about how high protein diets are a great way to lose weight fast. You do a Google search for “high protein diet.” The search spits back a handful of websites with oodles of advice on dropping pounds fast by following a high protein diet.
Before we dig into the science behind a high protein diet and weight loss, let’s first look at the concept of energy balance and the role each macronutrient plays in our body. If you’re not sure what all of this means, that is okay, continue reading and we’ll learn as we go.
What is Energy Balance?
First things first – let’s take a look at the concept of energy balance to better understand weight loss. Every day of our lives, we have energy entering our bodies (input), which is the food and beverages we consume. We also have energy going out (output), which is mainly our metabolism and various physical activities. If we want to gain weight, we need our input (food/beverages/calories) to be greater than our output (metabolism/physical activity). If we want to maintain weight, which is also known as being in energy balance, we need our input to equal our output. So, in order to lose weight, we need our input to be less than our output. This means we need to create an energy deficit.
We can create an energy deficit by:
- decreasing the number of calories we eat;
- increasing the amount of physical activity we do; or,
- a combination of the two. For more information about energy balance, check out this article by the National Institutes of Health.
Energy Balance and the High Protein Diet
So, what does energy balance have to do with starting a high protein diet? Let’s think this through…if you increase protein intake, but you don’t want to increase your total calories, that means you need to decrease your intake from another macronutrient. What is a macronutrient, you ask? It’s the fancy term we use for carbohydrates, protein, and fat. These are the nutrients that provide calories for our body. These macronutrients also act as the driving force in bodily functions that are crucial for maintaining our health.
If you increase the amount of protein you’re eating in a high protein diet, you need to decrease the amount of a different calorie-bearing macronutrient. This means eating less of either carbohydrates or fats. On a high protein diet, you typically decrease the amount of carbohydrates, and keep the amount of fat about the same.
What are macronutrients?
Now that we understand energy balance, let’s take a look at how each of the macronutrients are used in our body.
Carbohydrates are the main source of energy for our brain and our body. When we eat carbohydrates, our body takes and uses the amount of energy it needs at that time. If there are extra carbohydrates remaining, our body will store those as glycogen in muscles and liver and we can use that energy later. If we max out our glycogen stores and there’s still extra carbohydrates, our body will store the remaining as fat.
While carbohydrates are our primary source of fuel, we need protein for various functions that take place in each of our cells. Proteins are broken down into amino acids, which you can think of as building blocks for different functions. These building blocks are used to maintain muscle tissue, bone, cartilage, skin, blood, and also to build different enzymes, hormones and vitamins. Basically, amino acids help our bodies function at its best. Our bodies do a great job at regulating the process of making new proteins and breaking down old ones. If we eat too many protein calories, our body does have the ability to store the extra protein as fat. So, more protein does not necessarily mean more muscle.
Finally, let’s take a look at fats. Fats are an important energy source for maintaining health and providing fuel for various functions. The fat that our bodies store is our largest energy reserve, much more than the amount of energy from carbohydrate (glycogen) stores. Also, we need fats in our diet to assist with digesting and absorbing the fat-soluble vitamins A, D, E and K.
How does the high protein diet work?
Now that we understand energy balance and the roles of the macronutrients in our bodies, let’s put it all together and understand how a high protein diet works for quick weight loss. As discussed above, in a high protein diet we increase the amount of protein, decrease the amount of carbohydrate and moderate the amount of fat. Someone on this diet that wants to lose weight will need to create an energy deficit.
Lowering carbs means lower water weight, but higher cravings
If we lower the amount of carbohydrates, that means we are not giving our body as much of the main type of fuel it prefers. If we lower carbohydrates too much, we are not eating enough fuel to maintain normal functions. A couple of things can happen.
- First, you will nearly empty your muscle and liver glycogen stores pretty quickly. These stores will remain nearly empty until a sufficient amount of carbohydrates is eaten. Your body will start producing cravings in order
Now, when we store glycogen, we store it in a hydrated form. This means that we store it along with molecules of water. So what, you ask? Well, one of the reasons you might drop weight more quickly on a high protein diet is due to the loss of water that happens along with burning through those glycogen stores. We use up most of the glycogen and as we use it, the water goes with it!
Limited research on long-term effects of ketosis
The second thing that happens if you are not eating enough carbohydrates, the next fuel in line will be fat and fat stores. You might think this is good, and it might be for a little while. However, without enough carbohydrates, there is a byproduct that is created when your body starts to burn fat as its primary source of fuel, and these are called ketones. If your body continues to use ketones for fuel, you will enter a state of ketosis.
There is not a lot of research that has been done on the long-term effects of ketosis, which means it is not yet known whether it is safe to use fat as a main energy source for prolonged amounts of time. The moral of this story is, if you increase the amount of protein you are eating, and if you lower your carbohydrate intake, make sure you continue to eat enough carbohydrates to fuel basic bodily functions.
What else should I consider?
Now that you understand energy balance, the importance of each macronutrient, and how a high protein diet works, take a few minutes to consider the following questions:
What is your end goal?
Are you looking for a quick weight loss “fix”, or are you looking for lasting, sustainable weight loss? Remember that we all have a diet. Our diet is made of the the foods that we choose to eat on a daily basis. Start to think of food as your body’s fuel. The foods you choose affects the way your body feels. Choose foods that fuel your body, and that are realistic to continue eating throughout your life.
How much protein is “high protein”, and how much protein do I normally eat?
The amount of protein you should eat on a “high protein” diet is not clearly defined. A general rule of thumb is that eating 30% of calories from protein is often considered “high protein”, and 31-35% is often considered “very high protein”. Since the accepted range for protein is anywhere between 10-35% of your daily calories, according to the Institute of Medicine, first figure out where you fall within that range. If you’re eating close to 30% of your daily calories as protein, some might consider you to already be on a high protein diet.
If I increase protein and cut back on carbohydrates, what nutrients might I be missing out on?
Depending on the amounts you increase or cut back, it is very likely you will not get enough fiber. Most of us already do not get enough, and if you cut carbohydrates even further, you cut your chances of getting enough even further. Fiber is important for aiding digestion and supporting gut health, helping us feel full, and contributing to our heart’s health. A general rule for fiber is if you’re an adult woman, aim to eat 25 grams per day, and if you are an adult male, aim for 38 grams per day.
If I increase protein and cut back on carbohydrates, what nutrients might I be getting too much of?
Depending on the types of proteins you choose, you may be getting high amounts of saturated fats. Eating too many saturated fats can contribute to increased LDL cholesterol (LDL is often referred to as the “bad” cholesterol).
Be an informed eater. Aim to understand how the choices you make can influence your overall health. With that said, after learning a bit more and reading through this article, what do you think about high protein diets?