Know the long-term results of crash dieting.

Hormonal Consequences of Crash Dieting

Because the response to my blog post on fast versus slow weight loss was so strong, I decided to review a recent study about the long-term results of crash dieting.

More specifically, the study investigated what happens to appetite hormones after 10 weeks of dieting… one year later.

The Crash Diet Study

This year-long study involved 50 people with Body Mass Indexes (BMI) of between 27 and 40 (this is considered overweight or obese), who went on an extreme low-calorie diet for 10 weeks.

What’s an extreme low calorie diet?

In this case subjects were limited to between 500-550 calories a day. Since the average weight of the subjects was 209 pounds, this equates to around a third of their basal metabolic rate.

In other words, to live without moving at all, these people would burn about 1700 calories a day on average.

Without a doubt, these people were living pretty hungry for 10 weeks!

The Math

What this means is that on average the subjects were burning at least 1200 more calories per day than they were consuming.

Since fat has 3600 calories per pound, you would figure they should lose a pound of fat every three days. So at the end of 10 weeks (70 days) they should lose just over 23 pounds or 11% body weight in fat.

The Results

During the 10-week crash diet, subjects lost on average 20.7 pounds of fat and 9 pounds of lean muscle… but the results didn’t last over the next year.

As the year progressed, they slowly gained back half the weight they had lost. At first reading, this sounds pretty good. They lost a fair bit of weight in a short period, and then a year later, they were still ahead of the game.

The Short Term Hormonal Effects

The problem is what happened to their hormones that regulate appetite, hunger, and satiety… like leptin, ghrelin, peptide YY, and others.

After 10 weeks of starvation the volunteers had less leptin, peptide YY, and cholecystokinin, as well as more ghrelin and gastric inhibitory polypeptide.

As a result, the volunteers felt hungrier after the study than they did before it started. And this was not psychological, it was hormonal.

You might say this kind of makes sense because the subjects were just getting off of a crash diet and hunger is nature’s way of saying, “Hey, it’s time to eat something.”

It figures that crash dieting messes up appetite regulatory hormones for a short period, but until now, nobody had looked at the long-term effects.

The Long Term Hormonal Effects

Here is where it gets interesting and a little disturbing.

When the researchers looked at the long-term hormonal effects one whole year after dieting, the volunteers still suffered the same hormonal consequences as they had right after the diet.

And they still felt more hunger than before the diet took place.

Again it was not psychological hunger, it was the real thing.

Think about this again. A full year after dieting, the subjects still felt hungrier.

So it’s no surprise that most crash dieters regain their lost weight and eventually end up heavier than when they started.

The Take Home

There is a limit to how low a low calorie diet should go. There is still a debate on the magic number, but I would not recommend going any more than a couple hundred calories lower than your basal metabolic rate over a prolonged period of time.

Luckily, with RealDose Weight Loss Formula No.1 you can double your results even on a modest calorie restriction regimen.

And another thing to note is that the study tracked just one diet over one year. It is common for chronic dieters to do multiple crash diets in a year. If the hormonal effects from just one diet lasted for a year, imagine the hormonal effects of multiple crash diets.

My advice is to pick a plan, like our Fat Loss Fast Start Program or any other healthy long-term plan, and stick to it. And don’t fall for the tempting illusion of the crash diet.

Dr. Steven Sisskind, M.D.
Dr. Steven Sisskind, M.D.

Steve Sisskind, M.D.

Hi, I'm Dr. Steve Sisskind, Chief Medical Officer & Founder at RealDose Nutrition.

As a young physician, I struggled because my patients came to me with serious health issues, but I didn't have the right tools to help them. Medical school taught me how to put "band aids" on their symptoms with drugs and surgery, but not how to address the root causes of their problems.

Years later I discovered a better approach... based on the fundamental idea that the power of nutrition can transform your health and vitality. But there's a lot of confusion... What foods should I eat? Which supplements should I take? What does the science say?

I have dedicated my life to answering these questions... And I share this knowledge with you every day here at RealDose Nutrition.

I invite you to connect with me by joining my free private community. I've helped thousands of people and I know I can help you too!

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Sumithran P, Prendergast LA, Delbridge E, Purcell K, Shulkes A, Kriketos A, Proietto J.
Long-term Persistence of Hormonal Adaptations to Weight Loss. N Engl J Med. 2011 Oct 27; 365 (17): 1597-604.

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  1. How can i get a copy of your fat loss fast start program, because i have been battling with my weight fir 6 years. Ibam a diabetic and i have been trying different diets and exercising but my weight remains the same. Is there a shot i can get to help my hormones. Please let me know cause i need help with lossing this weight..

    • Dr. Steve Sisskind

      Hi Daniel,

      Thank you for writing in! The Fat Loss Fast Start Plan comes Free with every purchase of RealDose Weight Loss Formula No.1. That said, if you would like to have a copy sent to you, send us a quick email at As for the hormone shot, you may want to speak to your personal doctor about this. He or she may need to do a thorough evaluation to see if it is indeed what you need or prescribe an alternative option to help you get back on track. Hope this helps! Make it a healthy day!

  2. I’ve been on crash diet and regular weight fluctuations for more than 1.5 years .
    I’m experiencing heavy hair loss with miniturisation .
    Now I’m eating back normal since.3-4 months . Still I’m experiencing hair loss . Is there any cure for this

    • Dr. Steve Sisskind

      Hi Gautham,

      Thank you for writing in and for sharing your concerns with us! There are many reason why your hair is falling out and you can speak to your personal doctor if it continues or worsens over time. Your diet can help influence your hair growth but there is no guarantee that it will return to it’s original volume if the loss is brought about by other conditions. I suggest that you cease from embarking on crash diets and concentrate on making healthy long term dietary changes. Be sure to get plenty of fresh food into your diet and avoid heavily processed ones too. Hope this helps! Make it a healthy day!

  3. I enjoy reading your emails/posts/blogs. Is it possible to buy Real Dose products in Australia? Cheers Krystin

  4. Hello Dr Steven,
    I was doing hard job of loosing weight since last 9 month and I am very glad to saw the result and I lost almost 8kg since that time but I am still strugling to cut my low belly weight. I made a good shape exceot that part pls can you help any advise how can i cut that part.

    • Dr. Steve Sisskind

      Hi Murase,

      Thank you for writing in and for sharing your concerns with us! I completely understand what you mean and a lot of folks out there also have that same problem. If you have lost weight too quickly then belly fat is almost always a concern. There are a few tips I’d like to share: 1. Consume an optimal amount of protein. 2. Walking or jogging a few laps around the block daily. This will help tighten your core muscles. 3. Core exercises, simple ones, can go a long way in firming your middle area. Lastly, Eat a balanced diet with whole foods. This helps ensure an optimal intake of nutrients that nourish collagen formation, which promotes skin elasticity. Vitamin C, copper and silicon are especially important in collagen formation. Hope this helps! Make it a healthy day!

  5. Judith Dickinson

    Please explain what exactly is a basal metabolic rate and how does one determine his/her basal metabolic rate

    Thank you

    • Dr. Steve Sisskind

      Hi Judith,

      Thank you for writing in and for posting your concerns! The Basal Metabolic Rate is the number of calories your body burns while at rest. This is the minimal amount of calories your body needs to function and perform vital bodily processes such as respiration. There is a formula used to calculate your BMR and numerous apps have also been launched to do just that. However, for a more comprehensive and accurate result, I do recommend that you visit your personal doctor or nutritionist. Hope this helps! Have a healthy day!

      • Dr im crash dieter but when i stopped dieting my body thinks that im starving and i have low t3 thyroid hormone and high Leptin what to do about it

      • Dr. Steve Sisskind

        Hi Katty,

        Thank you for posting your concerns! A sick thyroid paired with crash dieting may make you gain instead of losing weight. The constant changes in diet plus sharp changes to your hormone levels is stressing your body to the point that it is constantly trying to store food for energy and keeping your metabolic rate low. I suggest that you work closely with your personal doctor in fixing your sick thyroid. Also, consider making small permanent healthy changes in your eating habits instead of subscribing into one kind of diet, that not be suited to your body type at all. Hope this helps! Make it a healthy day!

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