This article was originally written by the Sequence clinic team (now known as WeightWatchers Clinic).

Why Crash Diets Don’t Work

Published July 14, 2023 | Updated May 6, 2024

Our culture has normalized an obsession with body image, weight, and constant dieting, with many advice pieces claiming to share the “Quick Fix to Lose 20 Pounds!” or “How to Lose 30 Pounds in 30 Days”. These crash diets can seem appealing—they offer a “quick fix” and over-promise drastic results—but all is not what it seems.

The “dieting” mindset

Crash dieting often leaves us approaching food in a black-and-white mindset. We make a quick mental list in our heads of which foods will be in the “good” or “healthy” camp and which foods will be in the “bad” or “unhealthy” camp (later on I’ll explain why as a dietitian I avoid using those words to describe food and encourage others to do the same). Our brains instinctually like the simplicity of categorizing—which is why we are often drawn to these diet plans—when in reality, nutrition is a nuanced subject that requires an individualized approach.

If you have ever felt like you failed or had self-blame because you couldn’t stick with a diet, you are not alone. The whole point of these diets is to keep us coming back while at the same time convincing us we are the problem.

So, let’s dive into the science of why crash diets don’t work long term

3 Reasons Crash Dieting Can Be More Harmful Than Helpful In Our Health Journey:

1) Nutrient Deficiencies

When our bodies are in a state of restriction we are not getting the required nutrients we need. That may lead to nutrient deficiencies and cause long-term effects like hair loss, weak or brittle nails, fatigue, and irregular heartbeat. Both macronutrients (protein, fat, and carbohydrates) and micronutrients (vitamins and minerals) perform essential functions in the body—and getting enough of them is vital to our health.

2) Loss of Lean Muscle Tissue

Not only will a person lose a substantial amount of fluids along with fat, but severe caloric restriction can cause a higher amount of muscle tissue loss as well. Losing muscle means decreased strength and potential for bone fractures.

3) Decreased Metabolism

Our bodies automatically have something called “TDEE” which stands for Total Daily Energy Expenditure. It’s made up of four components, but the majority of TDEE will be determined by our Basal Metabolic Rate (BMR). Basal Metabolic Rate is the amount of energy our bodies need to function at rest. When a person loses weight, their BMR decreases in order to match the lower caloric amount being taken in and, in turn, halts weight loss—also called adaptive thermogenesis. From a biological perspective, this response is a good thing because our body’s main priority is keeping us alive, but long periods of this low energy intake can lead to adverse effects in our bodies.

How can we improve our nutrition in a healthy, sustainable way?

5 Tips Toward A Sustainable and Healthy Relationship with Food:

‍1) Protein At Every Meal

Studies support that this macronutrient is the most filling and can help a person remain satisfied and full. It keeps our blood sugar stable by slowing down the absorption of carbs so we don’t experience the effects a drop can have on us. Protein also protects lean muscle mass even when a person continues to lose weight–which is great because the more muscle we have, the more active our metabolism is. Consuming 1-1.2 grams of protein per kilogram of body weight every day is what we recommend.

2) Avoid Skipping Meals

Often skipping meals or going too long without eating can result in increased food cravings and over-consumption. Listen to your body and start to recognize physical hunger cues like your stomach feeling empty or growling. It’s important to eat when those feelings come on rather than waiting until you are ravenous, as this can often lead to overeating and leave you feeling too full and nauseous. Skipping meals can also cause you to miss out on essential nutrients to help your body function optimally.

3) Using Neutral Language Around Food

There is a fancy phrase for the idea that no particular foods hold moral superiority over others, and it’s called food neutrality. One of my favorite things to teach members is that “all foods have a place at the table” and whether you are eating broccoli or a piece of chocolate, there is some nutritional value to pull from in each item! Being mindful of how we describe what we eat is important for developing a positive relationship with food because it allows us to have variety and flexibility on a day to day basis without rules attached.

4) Focus On Addition Not Subtraction

The common theme with fad diets is the emphasis of restricting certain foods or decreasing calories. In order to foster a safe and healthy relationship with food, it is helpful to shift the focus away from what you have to eliminate and instead, focus on items you can add to a meal or snack to make them more nutritionally sound!

Make sure meals are filled with variety like protein, carbs, fat, and vegetable and/or fruit instead of low calorie options to serve us better in the long run for our health.

5) Daily Activity

Not only does exercise provide a wide array of benefits like maintaining muscle and bone health and lowering disease risk, but it also helps digest food better! Going on a light walk after a meal or snack can help aid in the digestion process.

The reward does not outweigh the risks when talking about crash dieting. The good news is there are other effective ways to lose weight and keep it off long term! Getting the right support system for you will be helpful in the long run.