New study shows fast food is indeed linked to obesity

• Fast-food consumption has strong positive associations with weight gain and insulin resistance, suggesting that fast food increases the risk of obesity and type 2 diabetes, conclude authors of a US study in this week's issue of THE LANCET.
• Obesity is increasing in the USA; at the turn of the millennium around 30% of Americans were clinically obese (having a body-mass index of 30 kg per metre squared or more) compared with 23% of the population during the period 1988--94.
• Mark A Pereira (University of Minnesota), David S Ludwig (Childrens Hospital Boston), and colleagues investigated the association between reported fast-food habits and changes in bodyweight and insulin resistance over a 15-year period in the USA.
• Overall, white women consumed less fast food (average 1.3 visits to a fast-food restaurant per week) than other ethnic groups (average 2 visits per week).
• By comparison with the average 15-year weight gain in participants with infrequent (less than once a week) fast-food restaurant use at baseline and follow-up (203 individuals), those with frequent (more than twice a week) visits to fast-food restaurants at baseline and follow-up (87 individuals) gained an extra 4·5 kg of bodyweight and had a 2-fold greater increase in insulin resistance.
• Dr Ludwig comments: "fast-food habits have strong, positive, and independent associations with weight gain and insulin resistance in young black and white adults.
• Fast-food consumption can be linked to adverse health outcomes through plausible mechanisms, and results from other studies lend support to our findings.
• In an accompanying commentary (p 4), Arne Astrup (RVA University, Copenhagen, Denmark), concludes: "Fast-food restaurants may argue that the evidence that customers are being super-sized by their meals is too weak.
• Recently, some major fast-food companies have taken positive steps by launching new healthier choices, such as porridge for breakfast, and fruit and vegetables for desert.