Snacking clue to obesity epidemic

Snacking and super sizing are two of the dieter's worst enemies, research suggests.

Foods like pizza are energy dense

The average daily calorie intake in the US has increased by almost a third in 30 years,reaching 2,374 kilocalories.

The influence of bigger portion sizes and excessive snacking outweighs the shift towards high-calorie foods, say experts.

Focussing on reducing how much and how often people eat could help tackle obesity, they report in PLoS Medicine.

."...for those trying to control their weight, it is important to manage both how much and how often they eat.”

Dr Áine O'ConnorBritish Nutrition Foundation

Obesity levels have risen sharply in many western countries since the 1970s. In the US, where the study was carried out, a third of all adults - more than 72 million people - are now categorised as obese.

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A team from the University of North Carolina analysed data from food surveys carried out in the seventies, eighties, nineties and the last decade. The surveys record all food and drink a person consumes over a 24-hour period. The average daily energy intake of a US citizen increased from 1,803 kcal in 1977-78 to 2,374 kcal in 2003-06. In the last decade of the study alone, the average daily calorie intake went up by 229 kcal.

Several factors are involved in energy intake - the number of calories (energy) in a specific amount of food (energy density), portion size and how many meals and snacks a day eaten. The researchers say that while all of these have gone up, increases in the number of eating occasions and portion size seem to account for most of the change.

They suggest efforts to prevent obesity should focus on reducing the number of snacks and meals a day as well as portion size

FACTS ON CALORIES

• In terms of nutrition, values are often given for the number of kilocalories in a food but referred to simply as calories
• The recommended daily calorie intake is 2,000 for women, and 2,500 for men (NHS Choices)
• Factors that influence energy intake include portion size, energy density and the number of meals, snacks and drinks consumed each day