Good news for anyone who is obese and trying to get healthier: Losing just 5 percent of your body weight can lead to significant improvements in insulin sensitivity, which can reduce the risk of major health issues like Type 2 diabetes and cardiovascular disease, according to a study published Monday in the journal Cell Metabolism.
“Even though five percent weight loss may not have dramatic cosmetic benefits, it does have significant health benefits,” said the study's author, Dr. Samuel Klein, director of the Center for Human Nutrition at Washington University School of Medicine. “You’re much healthier on the inside, and it’s a really reasonable and legitimate target for people with obesity."
This study clarifies conventional wisdom among obesity experts, who have traditionally advised patients to lose 5 to 10 percent of their body weight in order to improve blood pressure, cholesterol and blood sugar levels. But as anyone who has ever tried to lose weight can attest, there is a big difference between 5 percent and 10 percent.
"That’s a very vague, wide range," Klein said. "It’s much harder to achieve a 10 percent weight loss than it is to achieve a five percent weight loss."
Klein said his study shows that even just a little bit of weight loss is enough to improve health, and that people who can’t go beyond 5 percent shouldn’t feel like they failed.
As part of the study, Klein recruited 40 obese men and women for a randomized controlled trial of health outcomes at weight losses of 5, 10 and 15 percent. He randomly assigned half of participants to weight loss and the others to weight maintenance, and found that people who lost five percent of their weight had a loss of about eight percent in body fat mass, a seven percent decrease in intra-abdominal fat volume, and a 40 percent decrease in liver fat, which can contribute to nonalcoholic fatty liver disease and cirrhosis.
That five percent weight loss also significantly lessened the concentrations of levels of glucose, insulin and triglycerides in their blood, a decrease that's linked to a lower risk of cardiometabolic diseases like diabetes, heart disease and stroke. Finally, the five percent weight loss also resulted in lower heart rates and systolic blood pressure.
The subjects randomized to weight loss were studied three weeks after achieving eatch level of weight loss -- five, 10 and 15 percent -- and the more weight they lost, they more these health markers continued to improve. But there’s no question that a loss of just five percent resulted in significant improvements in health, said Klein.
"We did think that five percent weight loss would be beneficial, but we were surprised at how it affected so many organ systems simultaneously,” said Klein. Previous, smaller studies had indicated that a five percent weight loss wouldn’t influence certain health markers, he explained, but his study results show that even a moderate amount of weight loss can have metabolic benefits.
About one-third of American adults are obese, but Klein and others have questioned the relevance of the label “obese” as determined by the body mass index ratio. A. Janet Tomiyama, a researcher at University of California, Los Angeles, points out that despite long-standing, well-researched associations between obesity and chronic disease on a population level, a person's weight actually isn’t a very reliable predictor of heart health or diabetes risk.
Instead, Tomiyama points out, large portions of technically overweight, obese and morbidly obese people, according to the BMI ratio, are in fact metabolically healthy, while people of “normal” weight can also be metabolically unhealthy.
Asking metabolically normal but obese people to lose weight could be a waste of time, she argues, as well as contribute to fat stigma and “anti-fat bias."
If you're obese and your doctor has advised you to lose a little bit of weight to improve your insulin sensitivity or lower your blood pressure, even a little bit of weight loss can make a measurable impact on your health. Klein's hope is that this message becomes self-reinforcing, encouraging unhealthy obese people to maintain their weight loss and perhaps even keep going.
"If you can lose five percent, which is much easier to do than 10 percent, you will have significant health benefits if you can keep that way," he concluded.
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