Artificial sweeteners may contain zero calories, but some experts believe they may affect our hunger hormones, programming the brain to seek out sugar.

Certain 'man-made' foods can trick our bodies into over eating, according to some studies. Animal experiments found that linoleic acid, found in some oils, causes the brains of lab mice to become 'stuck' in feeding mode.

Sleeping even in dim lighting can cause weight gain, say researchers. Light interferes with the release of melatonin and can raise levels of cortisol. Experts suggest sleeping in the pitch dark and keeping electrical equipment at least three feet away.

Is your bedroom too warm? The body needs to cool down in order for melatonin and growth-hormones to be released. If it's too warm, you won't burn fat while you sleep.