Most of us assume exercise will help us lose weight by burning calories, but the surprising results of a study on children in Ecuador shed new light on the truth of that.
This research was done with children from two different groups of the indigenous Shuar people. One lived a hunter-gatherer lifestyle and the other lived in a market town and had a more urbanised lifestyle.
The hunter-gatherer children were lean and wiry, and spent their days running, playing and foraging. The town-dwelling children were heavier and more sedentary.
But here’s what’s interesting: they all burned about the same number of calories daily.
While this doesn’t stack up with our understanding of calories and activity, there’s other research to back it up.
Previous work with Tanzanian tribespeople has shown that although their lives are incredibly active and include hunting, digging, carrying and so on, they burn about the same number of calories per day as we more sedentary Westerners.
How can that be?
It’s explained as an evolutionary response to expending a lot of energy in daily life. Human bodies appear to compensate by expending less on other functions, such as immune responses or reproduction.
So physical activity didn’t account for the weight difference between the foraging children and their urban-dwelling counterparts. What did was diet.
The foraging diet was based around starchy foods like bananas and plantains. While the children were lean, their growth was often stunted — probably because they didn’t have regular access to good sources of protein — and they had frequent infections.
In comparison, the urban diet was closer to a ‘modern’ diet. It included more protein but also more processed food.
What we can take from this is confirmation that what makes the biggest difference to our weight is diet.
Exercise is hugely beneficial for health and can support healthy weight loss, especially for older bodies, by helping ensure we lose fat and not muscle.
But if your goal is weight loss, the first place to look is at what, when and how much you’re eating and drinking.
Having said that, a study published a few months ago found that exercise can help us lose weight, not by burning calories, but by adjusting our appetite hormones.
The only downside is we need to exercise a lot: around 300 minutes a week — roughly an hour each day on five days or, as they did in that study, walking 50 minutes a day for six days.