High protein diets, the favourite kind of diets in today’s world… We are bombarded daily with information how we need more protein, how it aids weight loss and boosts health, how protein powder supplements are an easy and convenient way to add more protein to our diets… There’s even a crowd of Paleo and ‘Primal’ people who cut out the majority of carbs and replace them with protein, they indulge in all things meaty and say that it’s the only way to thrive. Then, on the other side, there are raw vegans that say we don’t need more than 10% protein in our diets and carbs are what we really need. But the question is: Where is the truth?
This article has nothing to do with veganism. I am a follower of a plant-based diet big time, but I understand that what works for me will not necessarily work for you. This is why I do not believe in 5-10% protein nonsense. But I also do not believe in protein intake higher than required. Why? I’ll try my best to explain.
What is protein?
It is an essential macronutrient, a ‘building block’ that is required for many functions in the human body. It builds and repairs tissues, including organs, muscle, skin, hair and nails – a bad condition of the last three could sometimes be due to insufficient protein intake. It supports immune system, because our lymphocites and other white blood cells are actually proteins, so shortage of this vital macronutrient could mean poor immune function. Haemoglobin is also a protein and transports iron. Hormones such as insulin that delivers glucose to cells are also proteins. There are many-many uses of protein in the body. It just makes sense that the more protein we eat the better, right?
Let’s not forget about the carbohydrates
Another vital macronutrient, which people tend to neglect.
Carbohydrates are the primary source of energy that is readily available. When we eat a carbohydrate, it gets broken down to glucose, which is then delivered to cells for energy. The leftover is stored as glycogen in the liver and muscles and is utilised when exercising at moderate to high intensity or when the energy intake is insufficient. It is, however, a limited type of energy and it burns off quickly, so a continuuous top up is required.
The body has unlimited capacity to store… Fat
Fat is another essential nutrient, especially the monounsaturated type – our Omega-3 and 6. But fat is energy dense, and eating relatively small amounts of fat leads to large calorie intake. Fat in the body serves as organ protection and insulation, as well as a carrier for fat-soluble vitamins, which are A, D, E and K. Without sufficient fat intake and/or sufficient body fat it can become hard for the body to absorb those vitamins and a risk of deficiencies rises.
So the fat consumed in our diets gets utilised. But what if the fat intake is too high and we get more than we need? Due to the body’s unlimited capacity to store fat, excess dietary fat gets stored as fat.
Then what happens if we eat too much carbs? Well, unlike fat, the body’s capacity to store glycogen (glucose from carbs converted into energy) is limited. If we do not use the stored glycogen but eat more and more carbohydrates, the body doesn’t know what to do with them anymore, so it has to do what it can do best – store them as fat.
So, obviously, it is true what they say – if you eat too much carbs you can get fat. But let’s not be so quick to blame the carbs and say farewell. Let’s see first what happens if we eat too much protein?
This is the most interesting thing, at least to me. Protein plays an unarguable role in the human body. It is very (scratch that!) extremely important that we get enough protein. Just like with carbs and fat, there is a general recommendation that we get about 0.75 g per 1 kg body mass, sometimes up to 1 g per 1 kg body mass. So if you weight 60 kg, you need about 45 to 60 g protein a day. If you engage in physical activity, then your needs must be calculated according to your activity levels – and that is not just for protein; carbohydrate intake varies greatly as well!
But recently more and more researchers suggest that up to 2 g of protein per 1 kg body mass may be beneficial for weight loss when calories are restricted. Why? Because when trying to lose weight, some of the weight loss is contributed by muscle break down. Upping the protein intake slightly may help prevent this mucle break down and support tissue repair when on a calorie-restricted diet and ensures that you lose more fat.
Intake of 2 g of protein per 1 kg body mass is not, however, a high protein diet. It is simply higher than generally recommended protein intake, and it may not be beneficial for everybody. It is also wise to add, that research shows that there are clearly no benefits of intake higher than 2 g per 1 kg body mass.
But in recent years, with the protein supplements being marketed to us around every corner, people started to get the impression that protein is like a free food – you can have as much as you want ’cause it’s low to no carb and it’s good for you. Is it true?
Like I said previously, the body can store unlimited amount of fat, but not carbs, so it converts excess carbs to fats to be stored away for later. The same is true for protein. The body’s capacity to store protein is also limited, and beyond 2 g of protein per 1 kg BM there is no use for it anymore. The rest of unused proteins get deaminated – the amino group gets stripped off the protein and produces ammonia, which is later excreted, and the rest of amino acid is just carbon and hydrogen – just like carbs they are converted to glycogen if there is a demand for it. But what if there’s not? Then just like carbs, excess protein gets stored as fat.
- There’s not really much difference in the way your body utilises excess fat, carbs or protein. If any of those are eaten in excess, they get stored as fat.
Hence, it is important to know how much you need of each macronutrient and not overdo any of those.
- It is generally recommended that we receive about 45-65% of all energy from carbohydrates – because it is the most efficient source of energy, required for sustaining physical activity AND a healthy brain function. The recommended protein intake then is about 15-25% of energy, and there is really no need to go beyond that. The remaining 20-35% should go to fat, and it is highly recommended that we do not consume more than 35% fat because it also has no further use in the body.
So we see now that it doesn’t matter whether we eat too much carbs or too much protein. If there is no demand for it in the body, then it will be stored away as fat.
More than that, the process of deamination produces ammonia – a substance that is toxic to a human body. The body does a superb job to neutralise and excrete toxins through kidneys, because this is what it’s programmed to do, but it doesn’t mean that too much ammonia does not place a strain on kidneys. If a person is at risk of kidney problems then this raises the risks even further.
Another important note on the calories: too often when people cut down on carbs, they replace them with other macronutrients, either protein or fats. 1 g of carbohydrates is 4 kcal, and so is 1 g of protein! So if you replace carbs with protein, you still get the same calories. If you replace carbs with fat, you get even more calories in total because 1 g of fat is 9 kcal. This is not at all beneficial for weight loss. Most often when we cut down on carbs, weight loss happens for 2 reasons:
- We reduce the energy intake and consume less calories. This has a potential of kicking our bodies in the starvation mode and it will not only prevent us from losing fat effectively, it will actually make us store even more fat in the long run. It’s like a yo-yo dieting.
- Each gram of carbohydrates is bound to about 3 or 4 grams of water. When we cut down on carbs, we lose all the water attached to the carbs and that produces an immediate weight loss of about 1.5 to 2 kg, which is not further sustained.
The smartest way to reduce fat is through expending more energy than taking in (about 500 kcal deficit) and eating a balanced, unprocessed diet, at least most of the time. You can read more articles about smart weight loss here.
TO SUM IT UP
- Proteins, Carbohydrates and Fats are equally important for human body – each has its own role to play; we cannot really substitute one for another.
- Shortage of any of the macronutrients can be detrimental to health, carbohydrates included.
- Carbs don’t make you fat, excess carbs do. And so do excess protein and excess fat.
- Protein intake must be sufficient and you may require more protein during various stages of your life: when you exercise, when you are ill or injured or if you are an expectant mother. It is important that you meet your protein needs. It is equally important that you meet your energy and essential fatty acids needs too. As a rule, with the conditions mentioned above overall energy intake must be increased.
- Slightly increased protein intake may benefit weight loss and preserve muscle mass, but calories still must be restricted to make the weight loss happen.
- If you cut out carbs only to replace that energy with extra protein or fat weight loss will likely not occur.
- Excess protein places an extra load on kidneys and although not a problem in healthy individuals, it could be dangerous in people with pre-/existing kidney conditions.
- Overall, high protein diets are unnecessary and are no more beneficial than a well balanced diet, high in unprocessed whole foods. The source of protein matters too.