There are few absolutes in weight loss science. High-carb versus low-carb diets are still the subject of endless debate. Whether snacks make you slimmer or fatter is an argument for the ages. The evidence for calories-in versus calories-burned is even being questioned.
Amid this dissonant squabbling a clarion truth emerges: Eating at night is strongly associated with being overweight and obese. That after-dark nibbling makes you fat seems to be true for people of all ages.
Two new studies ad, ahem, weight to this consensus and offer some insight into why night snacking can make you overweight.
The first measured the effects of nighttime snacking on energy metabolism. The researchers looked at 11 healthy women, who either consumed a 210-calorie snack at 10 am or 11 pm over 13 days. After the 13-day period, researchers measured the basil metabolic rate for each group.
The conclusion: eating at night changes your metabolism for the worst. Eating the snack at night decreased fat oxidation (the rate at which fat is metabolized into energy and not stored as excess flab) and boosted total and LDL, aka "bad" cholesterol.
A similar study looked at 52 volunteers with the goal of understanding how sleep timing affects weight. The result: Eating in the evening or before sleeping seems to predispose individuals to weight gain because they consumed more calories at night (a phenomenon familiar to anyone who mindlessly munches brownie bites during Homeland).
The best advice: Don't snack after 6 pm, or—if you are a night owl—after 8 pm. And make sure the snacks you choose after dark are healthy and low-cal.