Researchers working with a hunter-gatherer tribe in Tanzania have claimed that the global obesity epidemic is more likely due to over-eating - rather than through increasingly sedentary lifestyles.

A six-strong research team - which included academics from universities in the US, the UK and Tanzania - studied the habits of the Hadza tribe, who still exist as hunter gatherers.

The findings - in a report called Hunter-Gatherer Energetics and Human Obesity - were published in the PLoS ONE journal today (26 July).

According to the researchers, there is evidence to suggest that daily energy expenditure is an evolved trait which has remained constant and is unaffected by diverse lifestyles.

Using the doubly-labeled water method, the team measured total daily energy expenditure (kCal/day) in Hadza hunter-gatherers to test whether foragers expend more energy each day than their Western counterparts.

While the physical activity level (PAL) was greater among Hadza foragers than Westerners, the results show that average daily energy expenditure of traditional Hadza foragers was no different than that of Westerners after controlling for body size.

The metabolic cost of walking and resting were also similar among Hadza and Western groups.

In its conclusion, the team wrote: "The similarity in metabolic rates across a broad range of cultures challenges current models of obesity suggesting that Western lifestyles lead to decreased energy expenditure.

"Our results indicate that active, 'traditional' lifestyles may not protect against obesity if diets change to promote increased caloric consumption.

"Thus, efforts to supplement diets of healthy populations in developing regions must avoid inundating these individuals with highly-processed, energy-dense but nutrient-poor foods.

"Since energy throughput in these populations is unlikely to burn the extra calories provided, such efforts may unintentionally increase the incidence of excess adiposity and associated metabolic complications such as insulin resistance.

Responding to the results, Fitness Industry Association CEO David Stalker said: "The relationship between exercise, diet and other lifestyle factors which have led to rising levels of obesity is a complex one, and I think it is overly simplistic and potentially dangerous to draw the conclusion from this research that exercise has no role to play.

"There is no doubt that a diet high in fat, sugar and processed products has contributed to this epidemic. However, we should be wary of viewing physical activity through an obesity-tinted lens and instead raise awareness of its vital role in improving and maintaining good health and preventing disease.

"Research published just last week in the Lancet has shown that the UK has one of the least active populations in the world, and this has been reflected in rising rates of obesity and non-communicable diseases, which put an unmanageable burden on our health service.

"An active lifestyle in combination with a balanced diet is the best approach to weight management, and this approach is now being acknowledged by the medical profession and key decision makers in government."

To read the full report on PLoS ONE, click here.