The mysterious reason that keeps you from losing weight

　　1. Do you sleep very little?

Lack of sleep reduces levels of leptin, a protein that regulates body fat, and increases levels of the growth-promoting hunger hormone (ghrelin), which stimulates food intake. What's more, it increases your hunger and appetite. If you think you burn more calories the longer you're awake, you need to think again. In fact, about 65% of calories are burned when our bodies are at rest. Over the past 50 years, the average amount of sleep we get per night has dropped from nine hours to about seven; over the same period, average body weight has steadily increased.

What should you do? Have a good night's sleep. Aim for eight hours of sleep and try to make it a regular routine. So, if you go to bed at about the same time every night and wake up at a similar time every morning, your hormones will be less disrupted.

　　2. Is the home too warm?

When it's cold, our bodies use calories to stay warm. Therefore, places with central heating and air conditioning consume less calories and tend to gain weight. For example, over the past 30 years, the average temperature in British homes has increased from 13°C to 28°C.

What should you do? Use central heating sparingly. If you feel cold, try to warm yourself up with exercise.