6 Reasons You Mess Up Your Diet

6 Reasons You Mess Up Your Diet.png

There isn’t one single factor that leads you to mess up on your diet, instead, it’s a combination of factors that lead you into temptation and away from achieving your goals. (Click to tweet this)

Your diet is one of the biggest defining factors when it comes to your ability to change your body. Get it right and you’ll be on your way, get it wrong and you’ll be stuck at square one.

This article explores 6 of the most common reasons you mess up your diet.

Failure will never overtake me if my determination to succeed is strong enough.
— Og Mandino

We’ve all been there…

A small unintended calorie surplus turns into an all-out binge.

The next thing you know you’re staring down the barrel of an empty Pringles can, whilst your friend tries to stuff the pizza boxes into the bin and someone in the corner moans about how full they are.

The causes can be seemingly endless; a last-minute dinner arrangement, the ‘just one more biscuit’ fallacy, a miscalculation of your calories or just about 100 million other reasons.

However, the result is always the same, you eat over your calorie allowance, mayhem ensues, and you’re left in an unwanted calorie surplus not just for the day but for the whole damn week.

Why Do You Mess Up Your Diet?

In my experience there is no single factor that causes you to overeat, it’s generally a multitude of factors that more often than not combine to create the perfect storm of eating too much and not giving a fuck (at least not in the moment). (Click to tweet this)

Let’s look at the factors that contribute to this perfect storm.


You know that your mood and decision making takes a knock when you’ve had a bad night’s sleep and are feeling tired, but did you also know that reduced sleep can influence how hungry you feel?

A study (1) found that “participants with short sleep had reduced leptin and elevated ghrelin [levels]” and concluded that “these differences in leptin and ghrelin are likely to increase appetite”.

Another study found that (2) sleep deprivation impaired the function of parts of the brain vital to decision making which could impair your ability to make informed decisions about which food to eat.

Hello, junk food!

Combine this state of increased hunger with one or more of the following factors and you can begin to see how a small slip up can become an all-out binge.

Shopping Hungry

It’s a universal saying, “don’t go shopping on an empty stomach!” but do you know why when you shop in a state of hunger you end up buying stuff you don’t need (or want)?

The responsible party for this phenomenon is Ghrelin (3), a hormone that stimulates hunger in your body particularly when dieting.

A 2011 study set out to try and measure this effect by recruiting a group of participants who were either;

  1. Injected with ghrelin

  2. Injected with a saline solution

Before being set loose to bid (eBay style) on edible and non-edible items.

Whilst participants were engaged in this behavior the researchers observed their brain activity using a fMRI machine.

They found that the participants given the Ghrelin were not only willing to pay more than the other participants for edible items but were less interested in the non-edible items, offering a lot less than the other group.

Given this link between hunger and a tendency towards poor food decisions, it’s no surprise that shopping when hungry often results in you eating over your calorie allowance either directly (you buy it and eat it) or indirectly (you stock your house with high-calorie foods you can’t resist when tired, bored, drunk, etc).

Speaking of being drunk, let’s look at the next factor.


Alcohol is often thought to be a big factor for weight gain with the belief often being it’s an all or nothing kind of scenario.

However, whether it’ll screw up your diet is not so clear-cut.

The truth is whilst alcohol when consumed with food tends to lead to an…

“increase [in] food intake, (probably through enhancing the short-term rewarding effects of food)”

…alcohol itself is not necessarily the lead contributor to weight gain, with researchers giving more weight to an individual’s “personality and habitual beverages preferences.” (45)

What this means is that if you’re drinking low-calorie drinks in moderation and account for it in your daily calorie intake, then alcohol won’t cause weight gain.

What will cause weight gain is the junk food you eat when under the influence of alcohol.

Which makes perfect sense…alcohol isn’t exactly known for its positive effects on decision making and it’s these poor decisions you make when drunk that leads you to mess up your diet.

Remember alcohol suppresses fat oxidation which allows your body to store fat and carbohydrates more easily but the actual conversion of alcohol itself into fat is negligible if it happens at all.

Woman shopping in a supermarket

Stress & Willpower

Do you eat more when you’re happy or sad?

What about relaxed or stressed?

How about a tough day compared to a breezy one?

If you’re like the vast majority of other people, then you will have noticed a trend towards bad eating habits and overindulgence when feeling down or stressed.

Add to the mix a social event where you expected or pressured into behaving a certain way or eating certain things and 9 times out of 10 the diet is out of the window.

To understand why we need to look at the results of a fascinating study (6) that measured the factors determining whether or not a judge would grant criminals parole at their parole hearings.

If you’re like me you’d expect that when ruling the judge would consider a variety of factors when making their decision. However, after looking at over 1,000 rulings spanning a 10 month period the researchers found that one of the biggest influences on the judge’s decision was the time of day.

The judge was most likely to rule favourably first thing in the morning with the chance of a favourable ruling steadily declining towards zero as the hours passed.

The same thing would then happen after the judge’s lunch break, rulings would start out being favourable before the chances of a positive ruling again decreased as the hours passed by.

Data from the study show the decline in favourable rulings over the day. Notice the spike after the judge had rested followed by a consistent decline all the way down to 0.

Data from the study show the decline in favourable rulings over the day. Notice the spike after the judge had rested followed by a consistent decline all the way down to 0.


The reason for this decline is due to what the researcher’s term ‘decision fatigue’ which essentially means that the more decisions you have to make, the more difficult it becomes to make them.

So as the judge continued to examine complex case after complex case the stress and fatigue of difficult decision making continued to build up until it was easier to just say no than engage the necessary brain power to make an informed decision.

It’s comparable to doing a set of challenging squats in the gym. With each consecutive squat, the movement becomes more and more taxing until you can’t squat anymore and have to stop.

This also what happens in your life every day and is made worse when you have a particularly stressful or taxing day. When this happens, you’ll find it that much more difficult to say no to high-calorie foods and prevent yourself from messing up your diet.

Combine this with the research (7) that shows some people will eat more of both calorie dense and high-fat foods when feeling stressed compared to those who are not stressed and it’s easy to see how after a long day your you’ll default to doing whatever is easiest even if you know it’s not good for you.

Hunger & Restrictive Dieting

We touched on this in an earlier point on shopping when hungry, but it goes without saying that hunger regardless of where you are or what you’re doing increases the likelihood of overeating.

To make things worse this effect is magnified if you’re also tired, drunk, dieting and/or fed up of eating a restrictive diet.

Which leads us nicely to my next point.

Your diet is not something you should be battling with, yet this is easily one of the most common reasons for people messing up. It’s the same old story of restrictive ‘clean’ eating during the week followed by the perceived ‘freedom’ of the weekend.

NEWS FLASH – if you need a break from your diet then you’re doing it wrong. (Click to tweet this)

Cutting out food items or food groups entirely is almost never a good idea, particularly if you like these foods.

It’s the age old, ‘you want what you can’t have’ situation where the end of the work week signals that it’s time to relax and you inevitably unwind by having all the things you couldn’t have during the week.

If the diet you eat is a struggle for you to stick to, then it’s not right for you and you need to make a change.

Chicken salad on a plate


The devil finds work for idle hands.

Those 7 words are probably the aptest description of what happens when you’re bored.

Except instead of some mythical red creature in a pit of fire torturing you for eternity, it’s your brain leading you into temptation and damning you to an eternity of mediocre results.

But what is it about being bored that causes you to eat?

In a word, dopamine.

Dopamine is a chemical in the brain responsible reward-motivated behaviour and is responsible for the good feeling we get when we accomplish a goal.

It has been found that eating can stimulate dopamine and the good feelings it provides.

Perhaps unsurprisingly junk food, particularly foods high in sugar, fat, and sodium are good at making you feel great.

This behaviour is backed by existing research (13) which shows that subjects who were bored ate more calories than those who weren’t, with additional research (14, 15) supporting this finding with results that indicated “that boredom markedly increases food consumption [in] both obese and normal [subjects].”

It’s no wonder you reach for that packet of Doritos, popcorn or biscuits when you feel bored, you’re almost hardwired to chase that dopamine high.

Estimating Calories

I’m sorry to be the one to tell you this but you’re just not as good at accurately estimating your calorie intake or calorie burn as you think you are.

What’s worse, it’s probably causing you to mess up your diet!

Research (8) shows that whilst those who are actively trying to change their weight are more successful that those who aren’t, everyone struggles to get it right, often underestimating the calorie content of their meals by up to 25% (9).

This can result in you eating up to 125 extra calories for every 500 you think you’re eating.

Think about it, if you eat a diet of 2,000 calories a day this could easily result in you eating 500 extra calories daily, and that right there is your calorie deficit dead and gone.

When it comes to exercise, research (10) shows that when estimating the number of calories burnt through exercise individuals overestimate the total by as much as 72%.

Which is absolutely staggering.

But not too surprising when you realise that research also shows (12);

“normal weight individuals overestimate EE [energy expenditure] during exercise by 3-4 folds [and], when asked to precisely compensate for exercise EE with food intake, the resulting energy intake is still 2 to 3 folds greater than the measured EE of exercise.”

Is it really any wonder that even when you’re sure you stick to your calculated calorie allowance that you still manage to mess up on your diet?

Chunk in any of the other factors listed here and you’re on track for disaster.

Takeaway Point

There isn’t one single factor that leads you to mess up on your diet, instead, it’s a combination of factors that lead you into temptation and away from achieving your goals. (Click to tweet this)

To stop messing up your diet you need to;

  • Make sure you sleep well

  • Stop shopping when you’re hungry

  • Moderate your alcohol intake and don’t binge when drunk

  • Use willpower to your advantage and work to reduce stress

  • Don’t use restrictive diets

  • Fight against or accept boredom

  • Don’t estimate your calories

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