Islamabad - That daily 5-mile run may not be burning as many calories as you think, a new study suggests.

In fact, the researchers found, moderate exercise - the equivalent of walking a couple miles per day - may be the best way to burn extra calories. Beyond that, the body seems to adapt its metabolism so that calorie-burning plateaus, no matter how hard you work out.

The findings may sound counterintuitive — or at least disappointing.

“The predominant view is that the more active you are, the more calories you burn every day,” said lead researcher Herman Pontzer, an associate professor of anthropology at City University of New York’s Hunter College.

This study, according to Pontzer, supports a different view:

“It’s really not a simple dose-response relationship,” he said. “The body adapts to exercise, and it begins adapting at a moderate level of activity.”

His team arrived at that conclusion after studying 332 adults, aged 25 to 45, from the United States, Ghana, Jamaica, Seychelles and South Africa. All of the participants wore a device that recorded their activity levels for a week, and the researchers used standard tests to measure each person’s total calorie-burning for the week. Predictably, people with moderate activity levels burned somewhat more daily calories than sedentary people did — an extra 200 per day, on average.

But more intense activity brought no additional benefit — at least as far as calories.

Pontzer stressed that exercise has many benefits for a person’s health in general. “There’s nothing in this study that suggests exercise is anything but good for you,” he said.

But if your goal is weight loss, exercise alone is unlikely to cut it. And that message, Pontzer noted, is not new.

“We know that diet changes are the most effective way to lose weight,” he said. “This study adds another piece of evidence to support that.”

Two researchers who were not involved in the study agreed that exercise alone isn’t enough.

“The reality is, exercise by itself is not great for weight loss,” said Dr. Timothy Church, a professor of preventative medicine at Pennington Biomedical Research Center, in Baton Rouge, La.

But, he added, exercise does boost weight loss from diet changes — and it helps people keep the pounds off.

Dr. Chip Lavie, director of exercise laboratories at the Ochsner Heart and Vascular Institute in New Orleans, made the same point.

“Also,” he said, “there are numerous benefits of exercise besides just weight loss.”

According to Lavie, those benefits include improved fitness (with high-intensity exercise generally getting better results), a lower risk of heart disease, stress relief — and fun.

But why wouldn’t greater amounts of exercise help the body burn more calories every day? Behavior could partly explain it, according to Pontzer: When people exert themselves at the gym or on a run, they might compensate by sitting or lying down more throughout the rest of the day. But Pontzer thinks there is also a physiological adaptation.

In an earlier study, he and his colleagues focused on the Hadza, a traditional hunter-gatherer population in Tanzania. The Hadza are highly active every day, Pontzer said — walking long distances and performing hard physical labor.

And yet, his team found, the average Hadza adult burns a similar number of calories each day as the typical American.

Health food should not be branded

as ‘healthy’

Calling a food healthy can actually put people off eating it, researchers have warned. Instead, scientists found people far respond better to healthy symbols.

Symbols that signify that something is healthy – rather seeing than the word ‘healthy’ itself – make people more likely to pick a nutritious snack, according to a new study.

Scientists revealed people are more likely to select healthy snacks - such as apples - if they see a nutritional, heart healthy symbol that signifies health - rather than the word ‘healthy’ itself

‘The word ‘healthy’ seems to turn people off, particularly when it appears on foods that are obviously healthy,’ said Dr Traci Mann of the University of Minnesota, who led the research.

‘The subtle health message, such as the healthy heart symbol, seemed to be more effective at leading people to choose a healthy option.’

Scientists from University of Minnesota, Twin Cities, conducted field and lab experiments to see how people responded to framing healthy food options.

One of the studies entailed 400 adult participants in a lab setting.

The researchers found 65 per cent of the adults took an apple, instead of a candy, if the heart healthy symbol was on the sign.

But, only 45 per cent took an apple if the word ‘healthy’ was printed on the sign.