can you ruin your diet with one cheat day


Sometimes our diet doesn’t go to plan.

Despite our best intentions and goals of getting leaner and fitter, occasionally life gets in the way and we go way over our calorie targets.

Heck, I’ve done it myself!

But how damaging can these days really be? Is it possible that one bad day can ruin your whole diet?

Today I will look into the science on this for you, and show you how to continue unlocking great results even if you’re not “on track” 100% of the time.

am I not eating enough to lose weight


Your diet is a numbers game, and unplanned days of over-eating can throw your numbers out of sync.

For example, if you are currently eating 1900 calories but have an off-track day on Tuesday your numbers might look like this:

  • Monday: 1900 cals
  • Tuesday: 3000 cals
  • Wednesday: 1900 cals
  • Thursday: 1900 cals
  • Friday: 1900 cals
  • Saturday: 1900 cals
  • Sunday: 1900 cals

In the scenario above, instead of having a 1900 calorie average we have a 2057 average, which pushes us above maintenance and might prevent weight loss or even lead to a little bit of weight gain.

These days happen to everyone.

Yes, even me! I’ve woken up countless times in the middle of the night with an empty family-sized chocolate wrapper next to me while Shaun T yells through the television screen about “Insanity!!!”. That’s life.

And I’d say that “ruin” is the wrong word.

In truth, you haven’t ruined anything because there are 3 ways we can completely wipe this out and remain on track.




Your body doesn’t care what day of the week it is.

This is a great thing, because it means you can average your calories out over the whole week if you want to. Better yet, you even have a bunch of options on how you’d prefer to do it!

Some people like a more agressive approach; i.e. they ate 1100 extra calories so they’ll go 550 under target for the next couple of days and get their calories back up to maintenance for the weekend…

… and some people like to make the deficit as small as possible; i.e. they’ll go 220 calories lower for the rest of the week.

It doesn’t matter which approach we use. In both situations we’ve created a weekly average of 1900 calories, bringing you right back on track despite a higher day.

See how it works:

can cheat day ruin your diet

does one bad day ruin your diet


There’s an old fitness saying:

“If you create a big enough fire, you can throw anything on it.”

Burning extra calories in the gym gives you an alternate way to balance your calories without impacting your food.

However, I’m not big fan of this approach, and I recommend using it sparingly.

You see, the more we train the bigger our food requirements become, so piling more exercise on top of your existing training will likely make you feel drained and hungry as f**k. If done regularly this can make your diet harder to stick to AND significantly increases your risk of injury.

Also, a 2021 study pubslished in Current Biology shows that more exercise doesn’t always mean better results. Resecarchers from the University of Ottawa, Canada, discovered that our basal metabolic rate (BMR) slows by an average of 28% when we significantly ramp up physical activity (!). They also suggested that people with more fat tissue could get even greater compensation, showing us that focusing on nutrition is probably the better choice when trying to drop body fat. (1)

So there you go; it can be done, just don’t do it all the time.

how to get back on track after a cheat day


This is a technique I began implementing with clients about 10 years ago, and it’s had a great rate of success.

It’s very simple – wake up the next day and start afresh.

Serously… don’t feel guily about it, don’t beat yourself up, just move on and re-focus.

I recommend using this method when an unplanned treat day leaves you with a calorie surplus that’s too difficult to balance out – even over the course of a whole week. For instance; if our example person with a 1900 calorie target ate 5000 calories in one day it would mean they had to go down to 1280 for the rest of the week, which is a nasty drop below maintenance that would probably be quite unrealistic and would make them feel like s**t.

Instead, just get back to maintenance calories and put it down to experience.

Now I know what you’re thinking…

… but won’t this hold back results???

Not really!

Being above your target may slow down weight loss progress for this week, but if it’s just one isolated day and you know it’s not going to be a regular thing then it honestly won’t even impact your results in the long run.

And if it IS a regular occurrence then we should look at why (perhaps the calorie target you’re trying to hit is too low).

can one bad day ruin your whole diet


The #1 ingredient in a successful diet is consistency, and in order to be consistent it must be sustainable. (2, 3)

So it’s crucial that you realize you’ve never “ruined” your diet.

In fact, you can ALWAYS sort it out and get right back on track.

I really want to drive that point home today, because when people believe they’ve wrecked their diet with one bad day it usually leads them to push the “f**k it” button and write off the remainder of the week. In those situations the real damage isn’t done on the off track day, but in the aftermath.

So now you have some highly effective strategies you can use the next time one of those days pops up. There’s always a fix.

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  1. Halsey L. G., et al. Energy compensation and adiposity in humans. Curr Biol (2021).
  2. Hall K. D., et al. Maintenance of lost weight and long-term management of obesity. Med Clin North Am (2018)
  3. Stewart T. M., et al. Rigid vs. flexible dieting: association with eating disorder symptoms in nonobese women. Appetite (2002).

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