Study shows that obese people who lost just 5% of their weight saw ‘profound benefits’ through better control of insulin in the liver, fat and muscle tissues
Even small reductions in bodyweight can have a profound impact on the health of obese people and their risk of future disease, researchers say.
A study of 40 obese men and women aged 32 to 56 found that losing just 5% of their weight led to substantial improvements in health through the better control of insulin in the liver, fat and muscle tissues.
Samuel Klein, director of the Center for Human Nutrition at Washington University in St Louis, said that expert societies generally recommend obese people to lose 5 to 10% of their bodyweight if they want to improve their health. But until now, there has been little research into the effects of losing 5% rather than 10%, which is tougher to achieve.
“It’s important to distinguish what benefits you get from 5% versus 10%, because losing 10% of your bodyweight is so much harder,” Klein said. “We were surprised to see really profound benefits in multiple organ systems simultaneously with only a small change in body weight. The biggest bang for your buck is with 5% weight loss.”
The researchers followed 20 obese people who maintained their bodyweight during the study, and another 20 who were tasked with losing 5% of their weight initially, and then 10% and 15% as the study went on. In the weight loss group, 19 people managed to lose 5% in weight. Of these, nine went on to lose 10% and later, 15% of their bodyweight.
Tests on the volunteers found that most of the improvements in so-called insulin sensitivity were seen with the first 5% of weight loss. For a person weighing 100kg, or 15 stone 7 pounds, that amounts to losing 5kg or 11lbs. The study is published in the journal Cell Metabolism.
“If you’re obese and have metabolic abnormalities, which these people did, and that means insulin resistance, some fat in the liver, but not yet type II diabetes, you’ll do yourself a remarkable benefit by losing only 5% body weight and keeping it off. You don’t have to become svelte and thin,” Klein said.
A host of diseases linked to obesity are caused by the body losing its ability to control insulin. When working properly, the hormone slows the release of fatty acids from fat into the bloodstream. In the liver, it suppresses glucose production, and keeps blood sugar low. In muscle, insulin stimulates the uptake of glucose, again keeping blood sugar down. “Insulin is a key regulatory hormone that underlies the pathogenesis of many cardio-metabolic diseases,” said Klein.
Stephen O’Rahilly, director of the MRC Metabolic Diseases Unit at Cambridge University said the results “provide a solid foundation for believing that even modest amounts of weight loss will bring health benefits.”
In England, the obese population has risen from 15% to 26% in the past 20 years [pdf], with the proportion classified as overweight hovering at around 37%. Only a third of men in England and about 40% of women have a healthy body mass index, defined as between 18.5 and 24.9. The rise in obesity in the UK is mirrored in other countries, such as the US and Australia, where obesity rates have reached 35% and 28% respectively.
“This is an important message for healthcare professionals to get across to patients in that even if this weight loss might seem small in terms of patient expectations, it conveys a significant health benefit. Clearly if you lose more weight the benefits are even greater,” said Jeremy Tomlinson, professor of metabolic endocrinology at Oxford University.
Tracy Parker, a heart health dietitian at the British Heart Foundation, added: “This study is good news for people who struggle with their weight as it suggests that even losing a small amount of weight can have a positive impact on heart health.
“As little as 5% weight loss resulted in improved blood pressure, levels of triglyceride fats in the blood, and blood sugar which are all risk factors for heart disease. Losing more weight was shown to further improve heart health. This study is a reminder of the benefits of gradually getting to a healthy weight. Setting realistic goals such as 5% weight loss is a good way to maintain healthy weight loss.
“When it comes to reducing your risk of cardiovascular disease, lifestyle changes do not just apply to losing weight. Giving up smoking, decreasing your alcohol intake and being more physically active all help reduce our risk of developing heart disease.”
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