Choosing a weight loss program isn’t that different from shopping—you need to think carefully before you hand over your credit card. Of course you want to find something that fits you perfectly, goes with your lifestyle and will never go out of style. But just because something looks like the miracle you’ve been waiting for, it could be the same pair of jeans you’ve tried on a million times before.

Sure, the fad diet du jour may have another adornment and a new celebrity spokesperson singing their praises. But sadly, the end result is always the same. That’s because fad diets don’t work. And—just like four-inch heels—they can be downright dangerous.

Spotting these shoddy trends isn’t always easy, but these tips should help you separate the real deals from the designer imposters. If you’re shopping for a weight loss program, always look for these four red flags.

1) One-Stop Shop

Fad diets boast fast results with minimal effort by making short-term changes to what you eat, often leaving lifestyle completely off the table. But a healthy diet is about health and quality of life, not just the number on the scale.

Things like physical activity, adequate sleep and stress management are crucial to healthy living. If a diet plan doesn’t mention them, you’ve likely got a flaming bowling shirt on your hands.

2) Put their Worth in Weight

Losing 15 pounds in a month sounds pretty good, right? Not to this Dietitian. Any fad diet that promises big results in a short time also comes with a bonus accessory: greater weight gain down the road.

You’ve heard of yo-yo dieting? There’s good science behind this and why it happens. In times of scarcity, your body protects itself by holding onto every calorie you eat. If you lose weight too quickly, you’ll end up with less energy, less muscle and a slower metabolism – a perfect recipe for weight gain.

3) Food-Shaming

Fad diets like to pick on the little guy, often choosing a new food to vilify with each new trend. And when demonizing a perfectly harmless food isn’t enough, many pick on vital macronutrients like carbohydrates or fats. Next thing you know people are cutting out nutritious whole foods or even entire food groups.

If followed over long-term, restrictive diets not only make you miserable, but also come with an increased risk of nutrient deficiencies and chronic disease. Any fad diet that suggests you banish healthy whole foods and buy a ton of supplements, is basically selling you shoes with no sole.

4) Emperor with No Clothes

Fun fact about fad diets: They don’t want you to know any better. Many take all the “work” out of eating, by selling pre-made meals or supplements. While that may seem convenient, they are basically creating a customer for life. Because when the program ends, old habits come right back—along with the weight.

Many fad diets also prey on people’s confusion about proper nutrition. Some actively de-educate their clients with their false claims and pseudoscience. Any weight loss program worth your time will be based on sound scientific evidence and will address the food skills and nutrition knowledge needed to keep you healthy for life.

The Bottom-Line

Fad diets are effective for losing only three things: your time, your energy and your money. There are no magic bullets when it comes to weight loss. No superfoods or supplements that turn you into a fat burning machine. And no diets that magically melt belly fat while you watch TV.

Just like fashion, the key to any healthy diet is one that fits, is versatile and will never go out of style.

Stay fabulous, not fad-bulous!