Diet plays “a far greater role” in obesity than exercise, say researchers behind a new study which explored the factors behind weight gain.
Experts are divided as to whether it is diet or a lack of exercise which is the main driver of obesity.
Calories consumed have to be expended as energy, either through physical activity or the processes within the body – known as basal activity – which use energy, such as food digestion.
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In terms of obesity, there has been a lack of clarity as to whether it is down to too many calories being consumed to be expended by activity, or if it is because there is not enough physical activity to use a reasonable number of calories.
Amanda McGrosky, from Duke University in America, examined data from just over 4,200 people with a wide range of diets and activity levels.
The diverse cohort was made up of adults across 34 populations in six continents, and included hunter-gatherer groups, pastoralists, farmers, and those from industrialised populations.
They examined the following:
- Totalenergy expenditure (TEE)
- Activity energy expenditure (AEE)
- Basal energy expenditure (BEE)
- Two measures of obesity: body fat percentage and body mass index (BMI).
AEE represents energy expended by exercise and is calculated by taking BEE away from the TEE.
The team’s findings were divided into groups according to economic development.
Initial results showed that while obesity was more prevalent in the countries that are more economically developed, more energy was expended overall.
However, after researchers adjusted for factors including age, sex and body size, AEE was still higher in more economically developed populations.
This key finding suggests a lack of exercise not likely to be causing higher BMI or body fat.
The authors said: “Estimated energy intake was greater in economically developed populations, and in populations with available data, the percentage of ultra processed food (UPF) in the diet was associated with body fat percentage, suggesting that dietary intake plays a far greater role than reduced energy expenditure in obesity related to economic development.
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“The hyperpalatability, energy density, nutrient composition, and appearance of UPF might disrupt satiety signalling and encourage overconsumption. Processing has also been shown to increase the percentage of calories consumed that are absorbed into the body rather than excreted.”
The authors stressed the importance of exercise due to the key role it can play in preventing disease and promoting better mental health.
Read more in Proceedings of the National Academy of Sciences.
