一项研究指出，节食会让你感觉悲惨，而且会增大你患抑郁症的风险。研究人员发现，那些成功瘦身的人感觉悲伤、寂寞和消沉的几率比体重保持不变或变胖的人大[微博]一倍。

广告上总是宣扬节食者变瘦后人生会大有改观。然而在成功瘦身后，节食者却发现除了体重减轻外，生活并没有变好。

而且，节食本身就是很困难的过程，不但需要相当大的意志力，而且为了减肥许多节食者不再下馆子吃大餐，从而失去了人生的一大乐趣，这也导致节食者情绪低落。

It's easy to assume that when you finally lose those excess pounds, life will change for the better。

But dieting can in fact make you miserable and more at risk of depression, a study claims。

Researchers found that losing weight didn’t make people happy. Instead, those who successfully slimmed down were almost twice as likely to feel sad, lonely and lethargic than those who stayed the same weight or got fatter。

The large-scale research, at University College London, found that the advertising industry tells dieters their lives will be transformed when they are thinner。

They then feel disappointed when they discover little has changed other than their weight。

In addition, dieting itself can be difficult, which in turn can cause people to feel down。

The findings come from a study of almost 2,000 overweight and obese men and women aged 50 and over。

They were weighed at the start of the study and answered questions about how often they felt sad, lonely and listless。

Four years later, some 14 percent of the volunteers had lost at least 5 percent of their body weight – an amount known to improve health。

Tests showed their blood pressure and levels of harmful blood fats had dropped, however their mood was also lower。

Those who had lost weight were 78 percent more likely to have symptoms of depression than those who hadn’t。

And importantly, the link could not be explained away by participants’ having fallen ill or suffered a bereavement or divorce during the intervening years, the journal PLOS ONE reported。

Researcher Sarah Jackson said: ‘We do not want to discourage anyone from trying to lose weight, which has tremendous physical benefits, but people should not expect weight loss to instantly improve all aspects of life。

‘Aspirational advertising by diet brands may give people unrealistic expectations about weight loss。

‘They often promise instant life improvements, which may not be borne out in reality for many people. People should be realistic about weight loss and be prepared for the challenges.’

The difficulties of sticking to a diet may also have a negative effect on mood, the researchers found。

Dr Jackson said: ‘We can speculate that the experience of restricting food intake and resisting temptations is bound to be hard, despite the undoubted satisfaction of seeing the inches go down and getting fitter。

‘Dieting requires considerable willpower and it might involve missing out on special meals and eating in restaurants. It is not necessarily the most pleasant experience for people。

‘Lots of people want to lose weight thinking it will fix all their problems. But while it will go some way towards fixing their health, it won’t necessarily make them happier in the short-term.’

She added that it is possible that slimmers are happier eventually, especially if they feel a sense of achievement from reaching their target weight and maintaining it。

Other possible reasons for the study’s findings include volunteers already having depression and that being a cause of the weight loss, or a stressful event such as losing a job leading to poor appetite。

The researchers said that whatever the reason, with 60 percent of overweight Britons trying to lose excess pounds, it is important that doctors and dieters are aware of the link with depression。

Dr Jackson said: 'Be aware of changes in mood and seek help if you need it. Don’t feel it is something you need to struggle with alone.’

Cary Cooper, professor of organisational psychology and health at Lancaster University, agreed that dieters often believe their life will change when their weight does。

He said: ‘Everything stays the same. The other things in life that troubled them are still there and that makes them depressed。

‘Don’t expect dieting to solve all the problems in your life. But it will make you fitter and healthier.’