When it comes to the "best" diet for most people, this one consistently ranks at the top of every list. If you can't afford a cruise to the Mediterranean (yet!), at least you can eat like the beautiful, long-living, and famously healthy people from the region. The Mediterranean diet teaches you to eat like a Sardinian, one of the "blue zones" identified by researchers as having a high number of people living past 100—by eating more fish, olive oil, healthy fats, and fresh vegetables. The point is to have not just a longer life but also a healthier and happier one, whether you're trying to lose weight or not. (Really—research shows that you can reap the benefits of the Mediterranean diet without cutting calories.)
If you’ve been eating fast food for years, get real about your approach: You’re probably not going to stick to an organic, gluten-free, paleo overhaul for very long. "You want to change as little as possible to create calorie deficit," says Dr. Seltzer, who insists the best way to support sustainable weight loss is to incorporate small changes into existing habits. So instead of giving up your daily BLT bagels in favor of an egg-white wrap, try ordering your sandwich on a lighter English muffin. Or say you eat a snack bar every afternoon: Swap your 300-calorie bar for a 150-calorie alternative. "Your brain will feel the same way about it, so you won’t feel deprived," he says.