Despite its good word of mouth, the paleo diet scores poorly when it comes to weight loss, convenience factor, and long-term sustainability. The fad diet's popularity may come from the simplicity: The idea is to simply cut out any foods that wouldn't be available in the Paleolithic era. That leaves no room for processed foods, refined sugar, dairy, legumes, or grains. You're left with meats, fish, poultry and fruits and veggies. Critics claim that wiping out entire food groups is unsustainable in the long term, making the diet a difficult lifestyle choice. That's not to say it's impossible to lose weight. If you calculate calories to burn more than you eat, like with any other meal plan, you'll drop weight. But study results are slim. One "underpowered" study found that 14 participants lost an average of five pounds after three weeks. If you're a carnivore, however, there are plenty of recipes to choose from.

Image via Getty

Despite being one of the top searched diets of 2016, the ketogenic diet wasn't one of U.S. News' best 38 diets of the year. It's an extremely low-carb diet, high-fat diet that was originally developed to treat epilepsy. You'll also limit proteins. The fad diet is a "sustainable form of fasting," Gary Yellen, a Harvard Medical School professor, told TIME. Since your body typically relies on carbs for fuel and you won't be taking any in, you'll be eating healthy fats for energy. Research does suggest that it works to treat obesity. According to Today, a sample menu for the popular diet might include eggs with olive oil and avocado for breakfast, leafy greens, salmons, nuts and olive oil for lunch, and steak, greens and more oil for dinner. Ask a doctor or dietician before taking this one on.

Image via Getty

Whole30 was on everyone's mind this year, but popularity doesn't necessarily yield good results: The fad diet was last on U.S. News' report for the second year in a row. It's meant to be a lifestyle transformation, changing the way you think about food and even claiming to help with medical conditions. You'll restrict yourself to no sugar, alcohol, grains, legumes, or dairy, for 30 days. It's a difficult plan to maintain if you're not accustomed to cooking all your meals yourself or shopping for very specific ingredients. There are also no "cheat" snacks: No hemp cookies or chia pudding, because the plan hopes to change the way you think about food. On the bright side, plenty who have attempted Whole30 agreed that the month was a challenge, and are still thrilled to have survived those 30 days. There isn't much independent research on Whole30 specifically, but a survey by the company claims that 96 percent of dieters lost between 6 and 15 pounds. The plan does have sample grocery lists and plenty of online support groups, so if nothing else, you'll be in it with a team.

Image via Getty