As a trainer and student, it is frustrating to see all of the misinformation about nutrition that is floating around the internet. It just serves to confuse and distract people from hitting their fitness goals.
I will be the first to admit as well, that we are far from understanding everything about nutrition due to lack of funding and current technology. Studies are still being published each year with contradictory evidence that just furthers that confusion.
For example, there is a running “joke” within the scientific community, that eggs and coffee have been labeled as both good and bad for you, with the narrative flipping every 5-10 years.
While there are a lot of situations where contradictory evidence is presented every so often for items like eggs and coffee, there have been a few myths of human physiology in respect to nutrition that have been proven multiple times, yet these myths still exist and are perpetuated and engrained into our society.
They run so deep, that even some health professionals believe that they are true.
Today, I will walk you through each one of these myths and explain why they are only myth and the studies that back up the information.
1) Your body can’t absorb more than 30 grams of protein
This myth came to fruition from some early studies that looked at the average amount of protein amongst different protein sources (think pork, whey protein powders, chicken, eggs, etc.) and the amount of time it takes something to pass through the entirety of the digestive tract (just the intestines).
The results came out to be an average of 5g/hr and a total time of 6 hours in the digestive tract. So multiplying those two numbers gave you a total of 30g.
That is where that magic number of 30 comes from, but we need to make a distinction between utilization and absorption. Your body does not regulate macronutrient absorption like it does with some micronutrients.
Our bodies are built to survive long periods of famine, so it will not pass on absorbing all of the macronutrients that it can in a given time. Even if you eat 100g of protein in one sitting, your body will absorb almost all of that.
The utilization piece is key, because our body is very efficient with how it uses these absorbed nutrients. It has been proven that amounts of protein over 20-30 grams, don’t have an effect on increasing protein synthesis.
So to some effect, the myth is right? Just poorly worded? Well, not so fast, because that is only half of the story. To increase muscle mass and “grow” our muscles, we have to be in a positive nitrogen balance. This is referring to the amount of nitrogen present in our body, and when it is in excess, we can build muscle.
When we are in a negative balance (not enough) our muscles are broken down to compensate. This recent study found that 70 grams of protein in one sitting drastically decreased the amount of muscle breakdown.
So while protein synthesis might max out at about 20-30 grams, that amount might not be enough to help you grow. So we can go ahead and cross this myth off of our list!
2) A High protein diet puts stress on your kidneys
This myth can also be broken down into two parts, with one you can actually help with. There is not a single study out there that demonstrates that excess protein consumption damages healthy kidneys.
Every study that shows protein having a negative effect on an individual’s kidneys, stems from the kidneys having a disease in the first place. In other words, if you have a kidney issues, a high protein diet is definitely not recommended.
This myth is a simple misunderstanding of the scientific studies presented. The second part to this story though, is that increased protein consumption leads to increased amounts of protein by-products, which are flushed out by the kidneys. To help your kidneys out, it is recommended to increases water intake when on a high protein diet.
3) Carbs at night will be stored as fat
This myth makes the most sense on how it was formed. I could see a person thinking that because we are less active at night, then carbs consumed before bed wouldn’t be utilized and stored as fat while we sleep.
The issue is, our activity levels only contribute to a small percentage of our energy used. Our resting metabolic rate doesn’t change that much when we sleep, so we essentially burn the same amount of calories as we would when sitting on the couch watching T.V. during the day.
So don’t fear carbs at night, as long as you aren’t over eating on your calories or macronutrients, you won’t gain weight. So if you had to skip breakfast one day, don’t be afraid to make up for it before bed.
4) Eating fat will make you fat
This myth also makes a lot of sense at first. Fat gets stored directly as fat, so eating it makes you fat, right?
No. In fact, consumption of dietary fats is vital to your health, survival and fitness goals. Dietary fats are broken down into triglycerides and used to make cell membranes (yes, every cell is incased in fat, well sort of.), certain hormones, and provide our body with energy via one of the three energy pathways.
Try your best to prioritize monounsaturated and polyunsaturated fats like olive oil, avocados, nuts, and fish. Saturated fats, like those found in eggs and animal proteins aren’t necessarily bad for you, but they don’t offer up as many health benefits as unsaturated fats.
5) All carbs are created equal
All carbohydrates have 4 calories per gram. That is where the similarities begin and end. Simple carbohydrates, complex carbohydrates and fibrous carbohydrates are all vastly different and are digested differently.
Simple carbohydrates, like cookies, fruit juices, sweets and refined/processed breads, are broken down and absorbed extremely quickly. This results in a huge spike in blood glucose amounts followed by a spike in insulin levels.
Insulin is a storage hormone, so therefore a lot of these carbohydrates get stored quickly. This is why sugary drinks and foods lead to weight gain and increased fat mass.
Complex and fibrous carbohydrates, like rice, veggies, beans, and sweet potatoes, are slowly processed and absorbed by the body. This results in a steady, but controlled release and rise of blood glucose. Because there isn’t a big spike of blood glucose, not as much insulin is secreted and so the carbohydrates are utilized now for energy, instead of stored as fat for later.
If you are looking to lose weight, I wrote a great article with my top weight loss supplement recommendations!