Your brain is a calorie hog (and other reasons not to fast/juice cleanse/starve yourself)

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Did you know that your brain and nerves take about half of your glucose (simple sugar we use for energy) a day? (About 500 calories!)

This fact is key in why yo-yo diets don't work and why people tend to gain more weight back after one. Your brain and nerves function best on carbs/glucose. Because of this your body stores branches of glucose in your liver (called glycogen) and breaks bits off when you haven't eaten for a few hours and your blood sugar drops. If you're very active you only have about 3 hours of stores, and if you're very inactive you can go about 24 hours.

So what's next? Once you run out of glycogen your body signals to release amino acids from your muscles. Your body can make glucose from your muscle tissue (and a fact that sounds scary to me, this process also breaks down your liver a bit too).In the first few days of your diet you aren't using your fat stores so much to fuel your body - 90% of your energy comes from your muscles breaking down.

After a few days your body switches to ketosis - where it fuels your body with fat, but it still breaks down some protein to help fuel the brain. (Your body's pH also becomes more acidic which leads to a sexy foul odor in your mouth called acetone breath.) In ketosis your appetite is suppressed and your metabolism slows down, partially because your muscle is wasting and demanding less energy.

On a low carb diet, the body does use some of the proteins you're eating to be converted for glucose for your brain, but some still do come from your muscle tissue.

So it honestly drives me a bit crazy when I see someone trying to lose weight on say, the 'master cleanse' which just consists of drinking water with lemon, cayenne pepper and maple syrup. I once saw a male model on his 20+ day of that!

I think many people get frustrated with their weight and decide to take 'hardcore' action and then go on super calorie restricted diets, but in the end those 30 pounds you lose may be (will probably be) even more gained. Sticking to a healthy diet for the long haul will not only make you skinnier, but healthier with more energy too (and you won't go through a couple of weeks of hating life and acting out at people too!) And if you hate exercise, at least go for a 30 minute walk, 5 days a week.

Remember if a diet makes you feel awful to follow, it's probably not a good diet!

Enjoy your day everyone!