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Eating less improves mood, sleep, and sex drive in healthy people, study finds

Life's full of trade-offs.

PETER DOCKRILL
6 MAY 2016
 

Calorie restriction isn't just something you should be doing if you're overweight or obese – studies have shown that a reduction in calorie intake could be associated with longevity, with research suggesting that when mice are given less food, it slows down a number of genetic ageing processes.

Now a new study suggests that healthy people can derive a number of benefits from simply eating less too – and not just in terms of losing weight (although, of course, that could happen too). When the diets of 218 healthy adults were followed over the course of two years, participants who restricted what they ate reported significantly better psychological effects, when compared to a control group that ate whatever they wanted.

 

The participants were men and women aged between 20 and 50 years old, and all had a body mass index (BMI) of 22 to 28, putting them in normal (healthy weight) or overweight BMI categories.

From this sample, one group was randomly assigned to reduce their calorie intake by 25 percent, while the other group didn't have to alter their regular diet. If you're thinking you'd much rather have ended up in the 'eat whatever you want' camp, consider this: two years later, the calorie restriction group reported improved mood and reduced tension, plus improved general health and sex drive.

What's more, after one year on the new eating regime, they reported enjoying better sleep quality. They also lost weight, dropping almost 12 percent of their body weight at the end of two years, with the mean BMI for the calorie restriction (CR) group sitting on 22.6 by the end of the study.

In contrast, the control group experienced almost no change in their weight after two years.

But before you rush to reduce your own food consumption, bear in mind it's not easy to slash your calorie intake by 25 percent. On the contrary, it's considered to be a pretty big adjustment.

"Even though they achieve those benefits, it is just really hard to adhere to these diets over the long term, at least in today's society," one of the team, Corby Martin from the Pennington Biomedical Research Centre in Louisiana, told Mandy Oaklander at Time. "They're minnows trying to swim upstream, in a world where it's very easy to over-consume calories."

 

That said, once you get a bit of momentum, it seems that adjusting to life with 25 percent less calories is doable – provided you get over the initial hurdle.

"What people report is that after they 'get over the hump' and start to lose weight, their hunger levels subside a bit and they start to feel the benefits of the weight loss," Martin said. "They find it easier to move around, their joints hurt less, they feel better."

Of course, nobody's suggesting we all just cut out a large chunk of our current food intake so that we feel better about our daily existence. But the value of the research is in pointing out that improvements in quality of life (QOL) that come from eating less aren't necessarily limited to obese people.

"Calorie restriction among primarily overweight and obese persons has been found to improve QOL, sleep, and sexual function, and the results of the present study indicate that two years of CR is unlikely to negatively affect these factors in healthy adults," the authors write. "[R]ather, CR is likely to provide some improvement."

The findings are reported in JAMA Internal Medicine.

While scientists don't fully understand why calorie restriction appears to impart such positive effects, the benefits of reducing food intake have been found in numerous studies, dating as far back as 80 years ago.

In 2014 a team from the NYU Langone Medical Centre found that, when fed 30 percent fewer calories, female mice showed less activity in almost 900 different genes linked to ageing processes in the brain, suggesting that eating less might slow down the cognitive decline that comes with age.

"Our study shows how calorie restriction practically arrests gene expression levels involved in the ageing phenotype – how some genes determine the behaviour of mice, people, and other mammals as they get old," said neuroscientist Stephen D. Ginsberg, at the time.

However, given the difficulties people face in cutting calories out of their daily diet, scientists are also looking at ways to achieve the same affects without having to sacrifice the amount of food we eat.

Another recent study in mice conducted at the University of Sydney in Australia found adopting a low-protein, high-carb diet might be just as effective as cutting calories, minus the pain of starving yourself.

"We have known for many years that caloric restriction diets increase lifespan in all manner of organisms," said one of the researchers, Stephen Simpson. "However, except for the fanatical few, no one can maintain a 40 percent caloric reduction in the long term, and doing so can risk loss of bone mass, libido, and fertility."

Of course, if you don't want to alter your diet at all, scientists are also looking into chemical compounds that might be able to mimic the effects found in calorie restriction. There's an awful lot of research going on in this area, so it's an exciting space to watch.

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