What To Do If You Mess Up Your Diet

By Ali Luke

It’s a situation familiar to many a hardened dieter. You’ve had a “bad day”. Maybe it was that unplanned cookie mid-morning, that bag of chips you shared with a colleague at lunch time, or that mid-afternoon candy bar … whatever it was, you feel like you’ve “failed”. You’ve broken your diet, and you might as well give up.

This line of thinking is why many of us are constantly on and off diets, yo-yo-ing up and down and feeling increasingly frustrated with our eating patterns, and with ourselves.

It doesn’t need to be that way, though – you can stop a dieting slip-up from becoming a dieting disaster. Here’s what you need to remind yourself (write these out and stick them to your fridge, if necessary):

  • One cookie won’t ruin your day
  • One skipped gym class won’t ruin your week
  • One day won’t ruin your diet

One Cookie Won’t Ruin Your Day

I call this the “one cookie” principle, but it applies to all sorts of other foods – so substitute your own weakness (bar of chocolate, slice of cake, etc.) where I’ve put “cookie”!

A single cookie has around 80 – 120 calories. One of those isn’t going to ruin your day. It takes 3,500 calories to gain a pound. That’s about 30 – 40 cookies, give or take a few. If you eat an unplanned cookie, give yourself permission to shrug it off. It’s a cookie; big deal.

What you must not do is give yourself permission to write off the whole day. “That’s it, I ate a cookie, I might as well give up.” Come on – can you imagine doing this in any other area of life? “That’s it, I overslept by 15 minutes, I might as well not go to work at all now.” Of course not … when you have a minor slip-up, you just get on with things as best as you can. That’s exactly how it should be with your diet.

One Skipped Gym Class Won’t Ruin Your Week

Maybe you’re okay when it comes to recovering from food-related mishaps. Perhaps your problem is exercise. It goes something like this: you end up working late on Monday, and missing your step aerobics class. And since you’ve now “failed” at your self-imposed exercise regime, you may as well not go to the gym at all this week…

Again, this is a silly way to think. You’re unlikely to see any dramatic loss of fitness based on skipping a single workout. Why not go for a late-evening jog or walk, so that you still get some exercise? Or try out the Tuesday class instead?

Don’t get hung up on being perfect. Again, in other areas of your life, you wouldn’t think in such “all or nothing” terms: if you missed a small project deadline on Monday, you wouldn’t give up hitting all your deadlines for the rest of the week.

One Day Won’t Ruin Your Diet

Here’s the biggie, the one that trips up most dieters. It’s the day from hell. It’s the day where you ate a cookie for breakfast, a chocolate bar mid-morning, and gave up completely by lunchtime. You scoffed a double-cheeseburger ready-meal for lunch, and numbed your feelings of guilt and failure with chocolate all afternoon. Now it’s evening, you’ve just polished off a pizza and a tub of ice-cream, and you’re giving up on your diet for good.

That’s your big mistake. Not eating the cookie, or the chocolate, or the ice-cream … but giving up. One day, however badly it goes, won’t be at all significant if you stick (more or less) to your diet for the next few weeks. Draw a mental line under the day (or a real line in your diary, if it helps), and start afresh.

Once you’ve realized that one cookie doesn’t ruin your day, though, you’re much less likely to have these day-long disasters. You might occasionally eat something you’d not planned, but you’ll shrug it off; maybe you’ll have a bit less lunch or dinner, or you’ll do an extra ten minutes in the gym, to get yourself back on track.

How do you stop your diet slip-ups from becoming diet disasters? Let us know in the comments…


  1. Ash G.

    I had 200-300 cals worth of sour cream and onion chips. I feel so so so guilty.
    lost a little under 4 lb this week. I was doing so well :(. Today was really stressful tbh. I’m about to go to the gym in a bit. I burn around 300 cals in 30 min on the eliptical. I usually do an hour work out i should be okay.but i’m still sooo mad at myself. Im sure the drop tomorrow wont be as much because of the chips’ fat and sodium content

  2. Kelsie Stahl

    I’ve lost 12 pounds and this past month I’ve ruined my diet so bad and gained some weight back. I feel like a failure. I really want to restart but I feel why bother I’m just going to mess it up again. I have no will power, I’m so weak and I hate myself for it. I struggle working out I never get used to it I constantly had to push myself when I was working out. I feel like I can’t do it without help, but I also don’t have anyone to help me. 🙁

    • Ted

      Perhaps your dieting is too strict or restrictive?

  3. Julie

    I’ve beeneating in a clean and healthy way, but this week has been so hard for me to stick to it though. I’ve been eating more than one cookie the last three days and telling myself I’ll get back tomorrow, tomorrow hasn’t show up yet though. And I’m feeling so sad like I’m a failure, I’m scared I’ll gain back the weight I’ve lost already.

  4. Nae

    Anddddd, I’m going out to dinner this Friday and plan on eating hot wings and fries!

  5. Nae

    I totally ate a brownie and I’m am on my fourth week eating healthy and working out . I haven’t cheated on my meals at all and I have a nutritionist and only missed two days in the four weeks. I also didn’t work out today. I just feel so terrible, I am really aiming to get this weight off me. Did I ruin it all 😩

    • Ted

      Hi Nae, You should look into flexible dieting. It allows you to have treats like brownies without messing up your diet. It’s truly life changing for some people, especially those that obsess about certain foods: https://healthyeater.com/flexible-dieting

  6. Em

    The worst thing is when you eat something you thought was healthy only to find out it had something like corn syrup or sugar in it! 😬 that’s what I get for not reading ingredients though. I’m not giving up!

  7. Lisa

    I feel somewhat better, but I had more than one cookie.

  8. Erica

    I just ate the whole bag of cookies and half a pizza, i feeel like i ruined my diet i may as well not workout today. What should i so i need help???

    • Ted

      Get back on the wagon tomorrow.

    • Lisa

      Go work out! I ate more cookies than I have ever eaten today so I am not going to ruin the whole day. I am going to the gym.

    • Ofri

      What is the logic in “I may as well not workout today?”
      Today you need it more than on “good” days, since you’re in a caloric surplus. This is precisely the defeatist mentality this article is about.