I recently attended a nutrition seminar on sleep and learned how important quality sleep is for our bodies and our brains. We need 7-8 hours of sleep every night - the average American only gets 6.3 hours. The presenter emphasized that although there are many important things going on while we are sleeping, the major purpose of sleep is to restore brain energy reserves that are depleted during our waking state. Interesting to note that while our brain is only 2% of our body weight it uses 20% of our total energy!
Here’s the part I want you to really pay attention to: When it comes to energy reserves, the brain is different from the body. Body cells can use carbohydrates, fats and protein for energy. However, neurons, the nerve cells that make up your brain, can only use carbohydrates. Yep... read that one again:
Your brain can only use carbohydrates for energy.
Here’s just a little biochemistry 101 for you. When you eat carbohydrates they are broken down into glucose to use for energy…your brain is happy. When you limit your carbohydrates, your brain says, 'hey I still need glucose but there isn’t any coming from carbs so I will break down her muscle mass' (fancy name for this process is Gluconeogenesis). You can, as a default back up plan, make glucose from muscle (keeps your brain still functioning but at the expense of your muscle mass which includes vital organs like your heart). Lastly, we can break down our fat that we eat and fat stores but the by product of breaking down fat are ketones, not glucose, and although our bodies can use ketones for energy, our brains CANNOT!!
So here are the implications of this. If you fast, go on very low calorie diets or limit the good carbs in your diet you will 1) break down your muscle resulting in a lowered metabolism and 2) your brain will not get the energy and oxygen that it needs to work optimally. What does that mean? 1) A lowered metabolism means you burn fewer calories and you have less energy. Typically resulting in weight gain. 2) A brain that is starved of energy is sluggish & foggy and consequently tends to result in making poor choices that often don’t support good health. Over time, this deprives the brain of energy and oxygen and increases the likelihood of dementia and Alzheimers.
So…back to square one. At least 50-60 % of your calories should come from whole grains, fruits & vegetables, 25% of your calories from good fats like eggs, avocados and olive oil, and 15 % from protein sources like lean meats, nuts, beans and dairy.