When we eat with other people, we consume, on average, 44 percent more food than we do when dining alone. Research published in the journal Nutrition found that a meal eaten with one other person was 33 percent larger than a meal savored alone. It gets scarier from there. Third-wheeling with two friends? You're looking at a 47 percent bigger meal. Dining with four, six, or 8+ friends was associated with meal increases of 69, 70, and 96 percent, respectively. Though part of this has to do with the amount of time we spend at the table when dining with company, another study from the journal Appetite found people who spent longer eating because they were simultaneously reading didn't eat significantly more, meaning time isn't the only factor at play here.

Eat This, Not That! Fix: You can still hang out with your friends. Just vary the activity once in a while, and include short runs or walk-and-talks. You'll save money and calories that are inflating your belly.