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Is sleep the key to weight loss?

Is sleep the key to weight loss?

An adult battling obesity who gets between six and eight hours sleep a night and has low stress levels is more likely to lose weight when dieting than their sleepless, stressed counterparts, according to a study published last month.

In recent years, much research has been carried out into how lifestyle is related to obesity. Poor sleep patterns, spending too much time in front of a screen (either a TV screen or computer screen), stress and depression have all been linked to obesity. The researchers in this study from the Kaiser Permanente Center for Health Research in the US wanted to look at the impact of all of these factors on obese adults enrolled in a six month weight-loss program.

The researchers recruited 472 men and women on a six month weight-loss program. The adults were all aged over 30 and classed as obese with BMI over 30 but weighing less than 400 pounds (around 180kg). The researchers recorded details of each person’s sleeping patterns, how stressed they felt, if they felt depressed or not, and how much time they spent in front of a TV or computer screen. These measures were taken at the beginning of the study and again six months later at the end of the study.

The weight-loss program was a series of weekly sessions with a nutritionist and behavioural counsellor. During each session they were asked to set food and exercise goals, and develop a weight-loss action plan. They were asked to aim to reduce their dietary intake by 500 calories per day, eat a healthy, low-fat diet rich in fruit and vegetables and do at least 30 to 60 minutes of moderate exercise a day. A diary was given out so that each person could record their daily food and drink intake and physical activity levels. At each meeting, the researchers also took measures of everybody’s weight.

At the end of the study, the average weight loss was 6.3kg. Over half of the adults had lost at least 4.5kg. However the researchers found that people who slept between six and eight hours a night were more likely to lose weight than those who had less than six hours or more than eight hours of sleep. Stress levels were also found to affect the likelihood of weight loss. Adults with high stress levels who slept for less than six hours a night were least likely to lose weight. Depression was also found to be related to how much weight a person lost: the more depressed a person was the less likely they were to lose weight. However, while this factor has been shown to be associated with obesity, the time spent in front of a TV or computer screen wasn’t shown to have an impact on weight loss in this study.

The researchers conclude that doctors and other healthcare professionals could use measures of sleep and stress to target people who may need additional help and guidance when it comes to losing weight.

Commenting on the research, Dr Stan Goldstein, Clinical Adviser at Bupa Australia, said: “The results of this study make sense, that not being stressed and getting a reasonable night’s sleep may help you be in a better frame of mind and so help you lose weight. The study confirms what we already know – if you are able to regularly have a good night’s sleep and  have relatively low stress levels, you’ll have fewer barriers to exercising. It makes sense that this increases the likelihood that you will then find it easier to lose weight.

It’s also an interesting study because people who slept for more than the often recommended eight hours also had trouble losing weight. Therefore, sleep patterns might be a predictor of future success or effort required to achieve the weight loss. And sleep, along with stress or depression, could be used as a measure or indicator for people who will need additional assistance to lose weight in a weight loss program.

“Overweight and obesity are a huge health concern affecting around two-thirds of the Australian population. The more we learn about what makes it hard for people who are trying to or would like to try to lose weight, the more we’ll be able to assist them”, said Dr Goldstein. “If you’re concerned that you’re overweight or would like to know more about maintaining a healthy weight, talk to your GP or an accredited practising dietician ... and to make it easier on yourself, try to get a reasonable amount of sleep each night.”

Key facts about overweight and obesity

  • One of the most commonly-used measures to standardise and define overweight and obesity in adults is the body mass index (BMI). Though it doesn’t measure how much body fat you carry on your body, it can be used to give an indication of whether you’re a healthy weight based on your weight and height. It is calculated by dividing your weight in kilograms by the square of your height in metres.
  • Generally, having a BMI of:
    • 20 to 25 indicates a healthy weight range
    • 25 plus indicates that you may be overweight
    • 30 or more defines you as obese
    However, BMI calculations can be inaccurate in certain populations such as high performance athletes, pregnant women, and the elderly – it is general guidance only so next time you’re at the doctors, talk to your GP about what weight range is healthy for you.
  • For the past 30 years, Australians have been getting progressively heavier, and we now have among the highest levels of overweight and obesity in the world. Around two-thirds of Australians over the age of 18 are now overweight or obese.
  • Being overweight increases your risk of developing health problems, including coronary heart disease, stroke, type 2 diabetes, osteoarthritis, some types of cancer, and reproductive issues for women.
  • Your weight is determined by the balance between what you eat and drink, and how active you are. You will gain weight if you take in more calories than you use up. To lose weight, you need to burn off more calories through physical activity than you take in from food and drink. This means eating fewer calories or burning off more calories (or preferably, both).

Read the study

Elder CR Gullion CM Funk KL et al. Impact of sleep, screen time, depression and stress on weight change in the intensive weight loss phase of the LIFE study.

Int J Obes advance online publication, March 29, 2011; doi:10.1038/ijo.2011.60.

Read the abstract.

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