We all know someone that is ALWAYS on a diet. They are the first to try the new “next best way of eating”. Think paleo, keto, intermittent fasting. If this person is you, I hope the information I share in this post will help you to understand why these diets don’t work for the long term; and can actually be detrimental to your health.
The common denominator with all diets is that they require calorie restriction. Which is what causes the weight loss, at first. However, after being on the diet for a while it is highly likely that you will plateau and your weight will not budge. Our bodies are extremely adaptable and amazing machines. They do whatever it takes to keep us alive. So, let’s talk about what our body does for us when we chronically restrict calories.
First, our brains are really good at dealing with starvation. When someone restricts calories, the brain understands restriction as that the human must be in a time of famine. So, the brain jumps in and says “okay, I’m ready for this; I know what to do to save my body.”
Second, our bodies do some amazing things to decrease our metabolism so that we don’t need as many calories to get through the day. In order to shut down our metabolism and protect our body weight; which is what our brain wants to do, the body naturally and quickly slows our heart rate, drops our blood pressure, slows our gastrointestinal system, and shuts down the warm blood flow to our hands and feet.
It is important to remember that everyone responds differently; just like some people who have smoked for 6 months develop lung cancer, while others have smoked for 50 years and are perfectly healthy. However, there are many medical consequences of chronic calorie restriction that are pretty consistently universal, whether you are thin or in a larger body:
- Heart rate slows way down – this is not the same as having an athletic heart. Heart rate decreases because your body doesn’t want to waste calories on extra heart beats.
- Blood pressure decreases – the brain puts your circulatory system into hibernation; which directly effects the strength of your blood pushing through your vessels.
- Core temperature falls – just like you might turn down the thermostat in your house to save on your heating bill; your body lowers your core temperate to save calories.
- Digestion slows – prolonged food restriction causes muscular atrophy, or weakness, in the entire digestive tract. The entire process of digestion slows to save calories.
- Warm blood flow to extremities slows down – hands and feet are not vital for survival, so blood flow will slow down to these areas.
- Early fullness – your body doesn’t want to spend an extra calorie on the movement required by your intestines. People who have chronically restricted may stay full 5 times longer than normal, which is a sign that your metabolism has slowed significantly.
- Constipation is almost universal in people who restrict calories – again, digestion and intestinal wriggles have slowed down; and the body will hold onto whatever calories it gets for survival needs.
- Bone density loss – this happens early and fast in restriction. This is one of the few complications that may never fully normalize.
- Women may lose their periods – the hypothalamus of the brain roles back in time to pre-adolescence, letting the body know that it is not a safe time to make babies. Women can stop making adequate estrogen, their uterus and ovaries will shrink in size, and their hormone system will get very quiet.
- Men can stop producing adequate testosterone – the same thing that happens in women will happen in men. Their hypothalamus lets their body know that testosterone is not needed for survival and they will stop producing adequate amounts.
As you can see, our body is more concerned with keeping us alive, than how we look in a bikini. The major problem with chronic calorie restriction, and why people often regret their yo-yo dieting habits, is that it can have detrimental and irreversible effects down the road – even 5-10 years. My recommendation: eat a well-balanced diet with adequate calories to keep your metabolism in check and your body running like the well-oiled machine that it is.