Focusing on sugar in the fight against global obesity could be misleading, according to scientists from the University of Glasgow.
Overweight people also need to reduce the amount of calories they consume from fat, they said.
The researchers examined the diets of more than 100,000 people in the UK who are part of an ongoing health study.
They found that fat made the biggest contribution to calorie intake of the people in the study.
Jill Pell, the director of the Institute of Health and Wellbeing and co-lead author of the report said: "The critical message is that people need to reduce their overall calories.
"If focusing attention on sugar results in people compensating by eating more crisps then we will fail to combat obesity."
Earlier this year, the UK government announced plans to introduce a tax on sugary drinks in a bid to curb consumption and reduce levels of childhood obesity.
Of those who took part in the study, two thirds (66%) of the men and more than half (52%) of the women were overweight.
On average, they consumed 12% more calories than those who were a healthy weight.
The scientists discovered that those who were overweight got a lower proportion of their calories from sugar than those who were on a healthy weight.
However, in absolute terms, they consumed more calories from both fat and sugar.
Other studies have repeatedly shown that people who eat fewer calories from one type of food simply compensate by eating more of another type - known as the sugar-fat seesaw.
Dr Jason Gill, from the Institute of Cardiovascular and Medical Sciences, who also co-wrote the report said: "People who are overweight and obese consume more calories than those who are normal weight.
"But they consume a smaller proportion of these calories from sugar and a larger proportion from fat. Thus it is important not to simply focus on reducing sugar intake; we need to emphasise reductions in fat intake as well."
The research is published in the International Journal of Epidemiology.