Losing Weight Could Make You Depressed, Study Says

Going on that diet may help you shed a few pounds, but it could also worsen your mood.

A new study at University College London examined 1,979 overweight or obese individuals in the U.K. to investigate the effects of weight loss on both physical and mental health. Unsurprisingly, losing weight led to significant physical benefits: those in the study who lost 5% or more of their original body weight over four years exhibited a drop in blood pressure and reduced serum triglycerides, both of which lower the risk of heart disease.

However, controlling for health issues and major life events that could cause depression, those participants were 52% more likely to report a depressed mood than those who stayed within 5% of their original weight. Though the study doesn’t prove that dieting causes depression, it does show that weight loss doesn’t necessarily improve mental health, as many people assume.

“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,” said lead author Sarah Jackson in a statement. “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.”

But Jackson points out that this negative effect on mental health could be more a function of the stress of dieting, rather than a consequence of the actual weight loss. “Resisting the ever-present temptations of unhealthy food in modern society takes a mental toll, as it requires considerable willpower and may involve missing out on some enjoyable activities. Anyone who has ever been on a diet would understand how this could affect wellbeing,” she said. “However, mood may improve once target weight is reached and the focus is on weight maintenance. Our data only covered a four year period so it would be interesting to see how mood changes once people settle into their lower weight.”

In other words, it looks like supermodel Kate Moss may have been way off when she uttered her infamous motto, “Nothing tastes as good as skinny feels.”

Write to Tessa Berenson at tessa.Rogers@time.com.