Body Mass Index (BMI) is defined as the ratio of weight (in kg) to height (in meters) squared and is an inexact measure of body fat, though it supposedly establishes cutoff points of normal weight, overweight, and obesity.

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Onge's study may be a step toward answering that "chicken-or-the-egg question" because it included only people of normal weight and therefore eliminated the influence of existing overweight or obesity, says Gina Lundberg, M.

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Anderson and her co-author are unable to say with any certainty that eating dinner together more often, getting more sleep, and watching less TV will help any given child lose weight, because of the other factors that may contribute to a child's obesity (or that may protect normal-weight children from becoming obese).

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Recent tests on mice found that those who eat when they would normally be asleep put on more weight than others who had meals at normal times, according to a study in the journal Obesity.

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