Could an apple a day keep the extra pounds away? According to a recent study in Food Chemistry, yes, because apples contain non-digestible compounds that promote the growth of good bacteria in your gut associated with weight loss.

How it works: These compounds--fiber and polyphenols--remain undigested until they’re fermented in the colon, where they act as food for friendly bacteria and help your body outweigh the bad bacteria that thrives on junk food, said lead study author and food scientist Giuliana Noratto. This restored microbial balance appears to reduce chronic inflammation, which increases the risk of obesity, and boosts feelings of fullness to help stave off overeating.

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“Obese people have an out-of-balance gut,” Noratto said. “So changing our gut bacteria via what we eat, making it similar to that of a lean person, could help prevent weight gain.”
In the study, obese mice that were fed apple compounds ended up with gut bacteria similar to that of lean mice.

But what kind of apple you eat may matter. Tart Granny Smiths reign supreme: They contain the highest concentration of fiber and polyphenols compared to varieties like Gala, McIntosh, and Golden Delicious.

Need more reason embrace the fall fruit? Previous research links apples to everything from a healthier immune system to a reduced risk of stroke, diabetes, high cholesterol, and cardiovascular disease.

Aim to eat an apple a day--or up to two or three, Noratto said. As for apple pie or crisp? Sorry, those don’t count: Cooking destroys the polyphenols in apples. Try some Granny Smith slices dunked in cinnamon-spiked peanut butter instead, or paired with a sharp cheddar cheese.

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