About You

A few important facts about how your body loses – and gains – unwanted weight

IMG_6787-thumbDespite occupying only 2 per cent of body mass, your brain burns a whopping 20-25 per cent of the energy you consume – it needs around 400 calories a day to carry out its metabolic activities. That’s before you even move a muscle. So just loafing about thinking about what you should be doing is a pro-active fat burning exercise in itself.

Your metabolic rate falls by around 15 per cent during sleep. If you think about it, this is a surprisingly small reduction for such apparent inertia. But don’t be deceived; as you slumber, blissfully unaware of the workings of your autonomic nervous system, your body is busy carrying out innumerable metabolic processes, and your brain is burning fuel furiously.

Sleep for seven to eight hours, in a darkened room, and your brain will switch on the hormones that initiate fat burning. At night, when you are in fasting mode, growth hormone swings into action. This noble, fat-mobilizing hormone stimulates the release of fatty acids from your fat stores to provide your brain and the rest of your body with the fuel needed to perform its innumerable metabolic functions. The secretion of growth hormone starts at the beginning of the first deep sleep cycle. However, peak GH secretion is inhibited if the onset of sleep is delayed. The sooner you go to bed, the sooner your GH can get to work.

The circadian rhythm (circadian in Latin means ‘about a day’) is an ancient inner clock located in the hypothalamic suprachiasmatic nucleus region of your brain which functions with near twenty-four hour precision. It responds to the rising and setting of the sun so that your patterns of sleep and wakefulness match the rotation of the Earth about its axis.

You suspect that exercise has little effect on weight loss – and you are right. If you are a lean adult, you will still have in the region of 80,000 calories of potential energy squirreled away as fat – enough to complete 25 marathon races. This supply is 40 times greater than the amount of energy stored as glycogen in skeletal muscle and liver. Good luck trying to burn that lot off in the gym, without changing your diet.

Did you have fruit juice with breakfast this morning? It could be stopping you from losing weight. Fruit juice contains concentrated fructose, which your liver is forced to convert into fat. Excessive fructose can also lead to the formation of damaged proteins that accumulate along your artery walls and contribute to plaque formation, which can result in thrombosis. So not only does your breakfast juice contribute to weight gain, it doesn’t do your arteries or life expectancy any good either.

You metabolise carbohydrates faster in the morning than any other time of the day.

Your stomach produces a hormone called ghrelin, which stimulates appetite by acting as a hunger signal to the brain. When you go on a calorie-restricted diet, you will produce more ghrelin. That way, your body ensures that eventually you will cave in and eat more.

Your fat cells produce another hormone called leptin, which acts as an appetite suppressant. It tells your brain when you are full. If you don’t get enough sleep, you do not produce enough leptin.

When you go on a calorie-restricted diet, you slow down the activity of your thyroid gland. As calorie intake falls, so too does your level of thyroid hormone output.

Stress can make you apple-shaped. When under stress you produce a hormone called cortisol. This hormone increases your blood sugar levels, and this sugar is converted to fat – and stored in your abdominal region.