Obesity is increasing in the USA; at the turn of the millennium around 30% of Americans were clinically obese compared with 23% of the population during the period 1988-94. Obesity causes an extra 300,000 deaths among Americans and health-care costs of $100 billion each year.

The effect of fast food on risk of obesity and type 2 diabetes has received little attention. 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.

Over 3000 young black and white adults were followed up with repeated dietary assessment. Overall, white women consumed less fast food than other ethnic groups. Change in fast-food frequency over 15 years was directly associated with changes in bodyweight in white individuals; a weaker association was recorded among black people. Increases in fast-food consumption was associated with increased insulin resistance in both ethnic groups.

By comparison with the average 15-year weight gain in participants with infrequent fast-food restaurant use (less than once a week), those with frequent visits (more than twice a week) to fast-food restaurants 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 view of the high and increasing rates of fast-food consumption, further research into the effects of this dietary pattern on public health should be given priority.”

MEDICA.de; Source: The Lancet