Are you hoping to quickly lose some extra pounds in time for bathing suit season? If so, you’re not alone.

People are drawn to diet fads this time of year because we want to get In-Shape for summer. Before you try a fad diet, however, beware — not every metabolism can handle the ups and downs that come with drastic diet changes. Fad dieting usually involves a short-term diet change that is not sustainable and rarely produces permanent weight loss. Here are some of the more popular diet trends of late and reasons why they won’t work.

The Master Cleanse

Also called the lemon detox diet, the decades-old Master Cleanse was originally designed to rid the body of toxins. Since the main phase requires users to consume nothing but a special mixture of lemon, water and maple syrup for 6-12 days, it’s no wonder weight loss can be rapid. But, this is hardly sustainable. The Master Cleanse is truly a “crash” diet and can be harmful to your health, given its lack of nutrients, protein, carbohydrates, fiber and vitamins.

The Atkins Diet

Perhaps the most famous of all the low-carb diet fads, the Atkins Diet is also one of the most limited. This plan touts itself as more of a long-term solution as opposed to a crash diet. But, like most diet fads, many people report having a difficult time sticking to it.

Phase I requires a limit of 20 grams of carbs per day with healthy carbs added in later phases. The diet’s high fat content and the limit on fruit and some vegetables have garnered much criticism from medical experts. They advise diversity is the key to a healthy diet and a full range of fruits and vegetables, even the starchy ones, is the best way to ensure you’re getting all the beneficial nutrients and fiber your body needs.

The Grapefruit Diet

As the name suggests, this diet fad is intensely focused on grapefruit juice, which is supposed to be consumed at each meal because of its purported fat-burning enzymes. While the grapefruit provides a large dose of Vitamin C, it can also interfere with common drugs, including statin drugs and antihistamines.

The diet is also high in protein and fiber but low in calories, with a daily intake of less than 1,000 total. Like the master cleanse, the grapefruit diet is a short-term diet (12 days) and very low on nutrients and protein.

It’s important to talk with your doctor before beginning any diet plan. This is especially true if you have a history of diabetes since many low-carb diets can change your blood sugar levels drastically.

Remember, when it comes to fad diet trends, if it sounds too good to be true, it usually is. Any diet that doesn’t include regular exercise as a major component simply won’t lead to healthy, sustainable weight loss.