The Science Behind Why Diets Don't Work

Have you tried to diet to lose weight, only to regain the weight back? Feel that you lack willpower to eat healthy? Always looking for the next scheme to get you back in your skinny jeans? Then this post is for you!  Today I share the evidence and science behind why diets don't work On a daily basis I have clients, friends, family and co-workers share with me the new scheme they are going to use to lose weight. A new diet. A new food group to avoid. How few calories they are going to eat. How many shakes they are going to drink instead of enjoying a meal. Maybe even a magical weight loss pill they are going to try. And all I feel is sadness.

Because I remember how it once felt to be desperate for results. How badly you want change.

I get it. I use to constantly think to myself why does my body hate me so much? Why can't I lose weight despite my new diet and exercise routine (i.e. only eat 1,200 calories and an hour of cardio daily)?

I bet you are even still thinking that you'll do one more diet, just one last time. And once you lose the weight you'll go back to normal eating.

Keep reading if that is you...

The Science Behind Why Diets Don't Work

After years of counseling clients and using the same techniques of cutting calories and following diets (unfortunately the techniques we were taught in school to use), I consistently saw that it never, ever worked. For myself, my friends and family, and for clients I counseled. The final result was always the same. Weight loss and "success" would occur at first. For probably the first month, maybe even a few months. Eventually though, it would stop working and my clients (or my friends or even myself) would lose perceived "willpower" and the weight would come back. (Read more on my story with diets here and here.)

I was constantly so frustrated that the advice I used on myself, and the advice I gave clients was not working. I mean...I was following the exact protocol I had been taught my whole life! The reality after dieting is that most people gain the weight back and an alarming 40% regain more weight than their initial starting weight. Going on a diet is likely going to increase your chances on gaining weight, not losing it.

Weight loss is not calories in versus calories out. It is so much  more complex than that.

As I began to stop counting calories, stop obsessing and living on and off diets I found freedom in food again. I started delving deep into the research on why my advice (and the way I had been taught to counsel my clients) wasn't working.

Today I want to show the SCIENCE behind why diets don't work.

Let's start first with the largest misconception with diets, that you stop dieting because you lack willpower.

Guess what? In terms of dieting, willpower doesn't exist.

Let me repeat that again. As far as how and what you choose to eat, willpower doesn't exist.

It is a man made, ego-driven, media-promoted idea that when you stop dieting it was because you are lazy and lack willpower or that you are not strong enough to keep eating your carrot sticks and bland chicken breasts. Willpower is not the same thing as motivation. It is a wonderful thing to be motivated to improve your health. It takes motivation and forming new habits to wake up and go to the gym daily, to food prep on a weekly basis and to make half your plate vegetables at mealtime. But you do not lack willpower if the ice cream is calling your name at midnight after you have only eaten a diet shake for breakfast, salad for lunch and chicken breast for dinner.

Why doesn't willpower exist? Because your body has a biological and psychological response to dieting. Studies show that after you diet your body changes in the following ways:

1. Your metabolism slows, taking longer to burn off calories.

Your body is wicked smart. It needs a certain amount of calories just to maintain your organs functioning, breathing and bodily function. For most people, this is at least (if not way above) 1,200 calories a day. Yet, eating 1,200 calories a day (and often way less) is the diet number we are all obsessed with.

Because your body is wicked smart, your metabolism will slow down and your body will learn to live off of less calories per day because it wants to STAY ALIVE. Your body doesn't hate you, it loves you. It is doing what it must to keep all the organs and bodily functions working. Unfortunately, the first bodily functions that stop working properly with calorie restriction is your reproductive system and digestive system. Both are VITAL in a healthy body.

The Biggest Loser study is a new research study that shows how the body and metabolism changes after calorie restriction and dieting. The clients followed a very strict calorie restricted diet and exercise routine and even years after participating in the show, their metabolism was slower than what it should be.

2. Your hormones will change. You will likely still feel hunger after eating.

Studies have shown a hormonal backlash occurs in defense to calorie restriction. Your "hunger hormone" grelin is increased after following a diet. While leptin, the hormone associated with hunger suppression and increasing metabolism, was suppressed. Another 20 hormones associated with hunger levels were also found to altered after following a diet compared to pre-dieting levels (read more in this study).

3. Food becomes more tempting.

Food preoccupies your mind, becomes more tempting and you cannot stop thinking about it. Your dopamine response to food alters and eating becomes more rewarding.

I was lucky enough to listen to a presentation by Dr. Mann from the Eating Lab on these changes that occur when the body is on a diet. You can read her book, Secrets from the Eating Lab, to learn more on the changes that occur to the body as a response to dieting.

The Science Behind Why Diets Don't Work

From a biological stand point, this is how your body fights to stay alive. Your body has a natural response (through the mechanisms described above) to keep working. This is how thousands of years ago we survived states of starvation. In today's world, we have chronic starvation because we are constantly restricting or calculating how many calories we are supposed to eat (rather than have our bodies tell us how much we need). The chronic restriction is then followed by binge eating on foods found in today's world (high in sugar, fat, chemicals and preservatives). It is literally a recipe for weight gain.

From a psychological response, diets don't work because restriction and deprivation never work. How many times have you told yourself that you are not allowed to eat the cookie? And once you "gave in" you ate at least double the amount you had planned on eating? Restriction leads to deprivation which leads to overeating which leads to guilt and then the restriction begins again. You have to stop placing foods off limits and stop restricting in order to stop overeating.

Your genetics play a large role in your size and weight. You have a set point (of about a 10-15 lb range) that your weight will stay, no matter your conscious feeling of what you feel you should weigh. Through lifestyle choices you can lose weight within that 10-15 lb range, but it is much harder to lose more weight once you drop further below your set point. This amazing neuroscientist describes perfectly what occurs when we diet and the set point thoery:

More Resources from Sandra on the consequences of dieting:

Weight and Health

Long Term Effects of Dieting

Early Dieting Predicts Weight Gain

Your turn: Share below your thoughts on today's post! Have you had the same experience when you tried to diet? Any questions on this topic that you would like me to share in more detail?

In my next post in this series, I will discuss what I believe does work and how to meet your goals without all the crazy dieting.