When most people decide they want to lose weight and “diet,” they start cutting out so many calories and adding excessive exercise to their routine. Cutting calories is the simple truth to success in the weight loss equation, but cutting too many calories has opposite effects. Keeping at a high calorie deficit for a while will work for a few day or weeks, but after that people see a plateau or a sudden stop and struggle. It’s your body waking up and realizing it needs to conserve whatever it can to keep going. Our bodies need some fat, which we use for energy, to survive. So what does your body do when it runs out of energy to use? Here are some of the consequences of not eating enough calories…

  1. Slow thyroid production – Your thyroid is responsible for fat, carbohydrate, and protein metabolism. With not enough calories, your body will slow down thyroid output in an effort to maintain some energy.
  2. Decreases muscle mass – Muscle highly depends on calories for maintenance. Muscle is the first thing your body looks to lose when it’s searching for energy. Your body will break down the muscle tissue and uses it for energy.
  3. Lowers testosterone levels –Testosterone is important for both men and women. Testosterone is anabolic to muscle tissue. Without it, it becomes that much harder to maintain and develop muscle mass.
  4. Decreases leptin levels – Leptin is one of many energy regulating hormones. More importantly, it’s a “hunger” hormone that tells you whether to eat or not. High leptin levels signal that it’s OK to stop eating, while low leptin levels are a signal to eat more energy. Because of this, leptin levels decrease in calorie restricted environments.
  5. Decreases energy levels – There are many physical actions your body takes when you’re not eating enough calories, but there are also some mental ones. Neurotransmitter production is limited, which can lead to a lack of motivation. It’s your body’s way of telling you to “slow down” – conserve your energy.


Here are some other symptoms that you may experience from not eating enough…


  1. Your Blood Sugar Is On A Roller Coaster: The most common issue that comes from under-eating is hypoglycemia, or low blood sugar. Common symptoms include hunger, shakiness, anxiety, dizziness, sweating, weakness, confusion, and changes in mood. Under-eating can easily cause hypoglycemia, especially when combined with exercise but this would be after a prolonged period of under-eating.
  2. Your Mood Is Totally Unpredictable: Most of us use the term “hangry” when we talk about getting so hungry that we get angry. Yes, this is a real thing but there is scientific evidence behind it. It’s an emotional state caused my inadequate food intake.  This starts from hypoglycemia mentioned before. When we have low blood sugar, our self-control starts to suffer because it is a cognitive process that is regulated in the brain and powered by blood sugar. Blood sugar effects more than just metabolism and the way your body feels.  It affects how your brain acts and how you think.
  3. You Can’t Fall Asleep (Or Stay Asleep): Insomnia and other sleep disturbances are one of the top symptoms experienced by people who are under-eating. It all goes back to blood sugar. As your blood sugar drops overnight, your liver must release its stored glucose (in the form of glycogen) to keep your blood sugar steady. If you’re constantly under-eating, your liver won’t have the glycogen stores it needs to keep your blood sugar stable, and your body must release stress hormones like cortisol and adrenaline to promote gluconeogenesis, the process of creating new glucose. If these stress hormones elevate high enough, they can actually wake you up in the middle of the night. Making sure you’re eating enough overall and including a carb and fat-dense bedtime snack 1-2 hours before going to sleep can help keep your blood sugar stable overnight, leading to more restful, uninterrupted sleep.
  4. You’re Chronically Constipated: There are a few reasons why chronic under-eating can cause constipation. The most obvious is that feces is made up of waste matter from the digestion of food, so if you’re not getting enough food, your stool won’t have much bulk to it. The less obvious, but more likely reason that under-eating can lead to constipation is due to the effects of undernutrition on thyroid hormone.
  5. You are Always Cold: Caloric restriction is known to cause a decrease in body temperature. A lowered body temperature can be due to a decrease in thermogenesis, since your body needs a certain amount of ingested calories to create heat, as well as due to the hormonal changes that come from caloric restriction. Low insulin can also lead to low body temperature, so people who follow a very low carb diet will experience this feeling also.
  6. You’re Losing Hair By The Handful: Hair loss is one of the first signs of nutritional deficiency. That can either be from calories or nutritional needs and often both. Hair loss is another common symptom of hypothyroidism, which as you’ve learned can develop from long term calorie restriction.


My best advice is to listen to your body.  If you are feeling a certain way, don’t ignore it.  That’s your body trying to talk to you.  When it comes to weight loss, it’s always important to start with higher calories and then to decrease from there otherwise you will put your body and hormones into shock with an immediate deficit and once you eat more calories even by just a little, your body will react and hold onto those extra calories.  Weight loss is a process and takes time, don’t try and take a short cut which will lead to unhappiness and long term problems that may be permanent!! Fuel your body and mind, when you make your body and hormones happy, it will reward you!