Why You Gain Weight on Diets (And The Simple Fix)

Why is it that most diets cause weight loss followed by a period where you gain weight? It’s a mystery that leads most people to believe that the entire diet industry is a hoax.

While there are many (many) bad diets that can easily be blamed for why you gain weight, most diets are designed to work. We know this because people lose weight and can keep it off. So what, then, causes the big divide between those that keep pounds off and those that gain them back?

The answer is something known as “set point theory,” which probably means nothing to you. But if you’ve ever found that you gain weight when you diet, it’s likely the missing piece of the puzzle that can change everything.

If more people understood that plateau is a part of weight loss, then they wouldn’t quit prematurely.

Long-Term Weight Loss Is Real (But You’ve Been Fooled)

I’ve been journaling–somewhat consistently–since second grade. While unpacking boxes after a recent move, I found an entry from 1991 (I was 9) that read: “I don’t have to always fit into big pants.”

I was that guy. The chubby guy who needed his pants tailored for his Bar Mitzvah because they didn’t make suits for young men with a waist so big and height so… restricted

If my story sounds cliche, well, it is. But it’s not too good to be true. The part missing from the fast-forwarded version is that I struggled with weight loss (and the dreaded weight loss plateau) and body image for years. I’d go as far as telling people I was allergic to chlorine to keep my T-shirt on in the pool. (I’ll never understand how I thought this explanation would work. It’s not like the shirt protected my skin from the water, but I digress… )

My ultimate success was a byproduct of many (many) failures and learning how to overcome times of despair and lost hope. I shifted away from gimmick diets and “four-week plans” and focused on blocking out my negative thoughts and becoming happier with who I was. Then I could finally focus on the other part of the weight-loss battle: building a realistic plan for my body.

It’s the same approach I’ve used to coach hundreds of overweight people to better health and fitness and more happiness. But it all starts with believing a simple truth that is starting to feel more like myth than reality: You can transform your body. Most people just do it the wrong way. Too fast. Too impatient. Too generalized. And too unrealistic.

I’ve worked with clients who have lost 100 to 200 pounds.  And most of the time, these successes happen over the course of months (or even years), not five episodes on a television show. At least, that’s the case for those who successfully keep the weight off.

This is an especially important point because some research (and recent media coverage) suggests that long-term weight loss is hopeless.  While many people do, in fact, gain weight they previously lost, it’s not because dropping fat is “mission impossible.”

Instead, it starts with changing your definition of “success,” setting aside instant gratification, and understanding how weight loss actually works. When that happens, everything changes and anyone can build a plan that ensures they’re not another sad statistic.

Why do you really gain weight?

First, some bad news: All nutritional approaches or diet plans stop “working” at some point. Weight loss stops. You don’t see changes, and you believe that either you or the plan are no longer functioning. The good news: When it appears to stop working, it’s actually still working.

Confused? Stay with me and it’ll make more sense.

We know that as you lose weight, your metabolism tends to slow down–although it’s not absolute. (This research reviewed 71 studies and didn’t find a significant drop in metabolism.) We also know that if you’re patient about (focus on losing one to two pounds per week at most), then you’re more likely to keep it off for good. But most people quit before significant weight loss occurs. It usually looks something like this:

Step 1: You lose weight (sometimes, a lot, and very fast)

Step 2: You stop losing weight

Step 3: You’re still not seeing any changes.

Step 4: Weight gain.

Step 5: You’re pissed off, frustrated, and quit.

This process usually happens in less than 6 weeks. If you believe some studies, the average person diets for an average of 6 weeks — followed by 14 weeks “off” a diet. That’s not a good balance of results.

The thing is — and what no one tells you — steps two and three (stalled progress/plateau) are often an important part of the weight-loss process.

Dropping one to two pounds per week is considered healthy, but it’s also the average. That means you might lose four pounds one week and zero the next. On those weeks when the scale doesn’t change, it’s not necessarily a sign that your body has reached its weight-loss limit.

To put it another way, your plateau is a  necessary part of the process. You must stall in order to move forward (again). And when you understand why–or, more importantly, accept this reality–it changes everything.

The Only Real Weight Loss Secret

Your body does not like change. I don’t care who you are; it’s very resistant to anything that takes it out of its comfort zone (a.k.a. homeostasis). When that change occurs–specifically when you try to lose weight–your body does everything in its power to adjust and get you “back to normal.” This is a process known as set point theory.

If you ask me, set point theory is the reason why so many people fail on long-term weight-loss goals. If more people understood that plateau is an expected and natural part of the process, then they wouldn’t quit prematurely. Sometimes the scale isn’t moving simply because your body is adjusting to change.

Here’s how it works:

We all have a “normal” body weight. Whether we like that weight or not is a different story, but this is the weight that we’ve come to “accept” as our own. We also have a look we desire, whether it’s your college weight, your pre-baby body, or where you were that one time you got super fit a few years ago.

Your mind wants to achieve your goals, but your body wants to cling to what’s familiar. So when you try to change, physiological reactions occur to suck you back into the body you’ve known for so long.

The more weight you lose, the harder your body works to resist that change, or even pull you back to your old weight. It does this by slowing your metabolism (comparatively) and increasing your hunger. Sucks, right?

Just wait, it’s not all doom and gloom. If you can hang in and resist the urge to quit, these changes are temporary and can help ease the permanence of your weight loss.

Set points are not carved in stone. It’s more like frozen in carbonite, a la Han Solo. You can undo the process by changing your body and allowing your body to adjust. This is why plateaus can be so deceiving. Your body is adapting to its new reality. Once it does, that’s when you’re ready to take the next jump and see a “whoosh” of new weight loss.

Everyone’s set point is a little different, so there’s not one rule for how long you have to wait. The more weight you have to lose (say, more than 50 pounds), the quicker it can happen initially without hitting your set point. If you want to lose closer to 15 or 20 pounds, you might hit a wall after the first 10.

This is why you’ve seen so many magazine cover lines about “How to Lose the Last 10 Lbs.” Those should really say, “How to Be Patient After You Lose the First 10 Lbs.” But that doesn’t sound as sexy.

Once you hit your set point, your body likely needs anywhere from four to eight weeks to adjust to your new weight. Then you’ll establish a new set point, and your body will respond like that’s your new normal.

It doesn’t sound that exciting, but it’s better than you think.

If you go from 200 to 180 pounds or 150 to 130 pounds and wait out the set point process, your body’s drive to move back to the old weight has changed. It becomes much easier to stay at your current weight because your body no longer thinks it’s outside its comfort zone–and you’re able to start losing weight again. On the flip side, it becomes much harder to gain weight, as well.

The result: you don’t feel like you’re constantly following a pain-in-the-ass plan. That’s why long-term fat-loss never occurs in 30 days or anything magical. It’s a process.

Finding the right eating approach is about seeing the long-game. Almost any plan can deliver the quick results. Ignore those. Instead, focus on what you think you can do for six to 12 months. When you do, you won’t be as frustrated when you hit the set point. Instead, you’ll be buying time–not buying a new approach (literally)–until the weight loss starts again.


Winning the War on Hunger: Practical Solutions to Overeating

Fix Your Diet: Understanding Proteins, Carbs and Fats

Big Meals vs. Small Snacks: What’s Best For You?


  1. I am trying to increase my weight and find it tough for me. I have slightly less weight as require. I have found some useful tips from your content and these technique looks like I did not try before. After reading your ideas, I feel confident to gain weight. Thanks

    1. Happy to hear we helped bring back some of that confidence. Thanks for reading!

  2. Thank you for this note! This hits sooooo close to home, you have no idea. Today I hit week 6 of no alcohol + daily workout (1hr cardio, 30-40 min weights) + fasting and I just went up in my weight, and just last week I lost 4.1 lbs. I went up from 181.7 to 182.0 so it was barely nothing but still coming from losing 4.1 to not lose anything was a shock, specially with the amount of effort I’ve been doing @ the gym.

    Your article help me to not feel that bad and understand something I didn’t before. I will keep pushing and see what the results are for the next weeks.

    Thank you.

    1. Thanks for sharing your story, JP!
      Keep up the good work. Happy we were able to provide some guidance.

  3. I just want to say thank you for explaining the set point so clearly. I freaked out this morning when I stepped on my scale and I gained yet another 2 pounds. I know that two pounds is really nothing to worry about but this was the third day of a 2 pound gain for a total of 6 pounds in three days.
    I started 3 months ago (again) eating healthy. My diet consists of leafy greens, veggies, very little whole grains, good fats and lean meats. I track what I eat on my fitness pal to help me stay aware of what I eat. It was slow at first but I managed to loose 20 pounds. This was huge for me since I have thyroid problems and loosing weight has been a struggle for about 15 years now.
    I have been on every diet “plan” In the past and always quit and threw in the towel when I reached the set point. I thought I just was destined to be fat and that’s all there was to it. Not knowing what was happening, I just gave up and went out for some ice cream.
    Ok, so I have one question , what do I do now? Do I keep on eating healthy and exercising? Isn’t there something I can do to speed up this reset of my metabolism ?
    Sorry, that’s three questions.

    1. So do you continue your diet and exercise plan as normal and just wait and the scales will start to go down again?

  4. One of the most straight-forward, on-point, explanations regarding the weight loss and weight gain conundrum that I’ve come across on the Internet. Simple, real-world advice for anyone who aspires to lose a few pounds and keep it off in the long term. Well presented.

    1. Thanks for reading and for sharing the kind words, Gary!

  5. Thank you so much for this. My body has been at a stand still. I am not able to get my weight lower than 185. Im 5’8. I had my son 18 months ago. I was working out 5 days a week and eating nothing but veggies and meats. I lost a total of 50 pounds if you count baby weight. But I want to be 160 so badly and my body wont budge. Infact, I have gained weight recently. Im very frusted. This really helps me see I wasnt giving my body enough time to adjust. I just need to be patient.

  6. Thank you for sharing valuable information. I liked the approach you shared that is to focus on Easy to follow Diet for 6 to 12 moths. On point!

  7. Hi!

    I’m a part of the FLA and I love it! I haven’t hit my goal weight so I continue with the plan.

    This article explains why I’ve been hovering at 140 lbs for the past three weeks after losing almost nine pounds. It is becoming disheartening but I keep going.

    Do I continue with my current plan of approximately 1400 calories/day? Honestly, the past two weeks I’ve been at 1100 – 1300 calories/day hoping that it would change the scale. (I lost 0.2 lbs one week then gained it back the next.)

    I appreciate the help!

    Thank you,

    1. Hey Angela — We will send you message via email to help the best we can.

  8. Would you recommend adding calories gradually to boost metabolism or would you say to stay at what you are doing?

  9. Thank you for this perfect article. I lost 10 and then stalled out so I started googling why. Then I found your article and God bless you for sharing this info. I really needed to read this today.
    Keep at it friends!!!

    1. Thanks, Kimberly and great work on losing the weight. Celebrate the wins!

  10. Best article on diets and plateaus I have ever read. It’s brilliant!!!
    My body stalls all the time, gains on 800 Cal’s a week (I am disabled so not burning calories), and will plateau for 4 wks (then I fall off my diet). If I had read this, I don’t think I would have!!
    Do you have any tips when I plateau, to kickstart the weight loss again? Or is it a case of waiting it out, and eventually I will start looking again? Many thanks

  11. I really needed this right now to continue to be disciplined with my new way of eating and daily exercise. Thank you!

  12. I see it in my family all the time. I don’t have a weight problem, but my daughter does. She has started so many fad diets, and then quits. Because she’s too impatient. I will pass on this article. Thank you.

    1. Thanks for passing on the article, Bridget! Hope it can be helpful for those you love.

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