A calorie deficit is an important, vital part of the weight loss process, without which fat loss simply won’t happen. However, in your quest to lose a little weight, look a little better and feel a bit stronger there is a point of diminishing returns.
A point at which you can get too much of a good thing and the very thing that is helping you lose weight starts producing negative side effects which ultimately slow down your progress and leave you feeling worn down and fed up.
When it comes to weight loss the truth is it just won’t happen if you’re not in a calorie deficit. You need to burn more calories per day than you eat to lose weight.
You see, weight change follows the rules of the energy balance equation, which states that you will always be in 1 of 3 states of energy exchange;
Without being in a calorie deficit you will not lose weight.
Note: if you eat too much when using any of these diets, you will gain weight which highlights the power of calories not food choice.
When eating in a calorie deficit you’re purposefully giving your body less energy than it needs each day to function.
If this is sustained, then it will result in weight loss over time. However, it also produces several other side effects that conspire to make you feel like crap and your deficit harder to maintain;
Different individuals will suffer from these effects to varying degrees, but the outcome (eventually) is always the same…you suffer because you’re dieting too hard.
If left unchecked the side effects of being in a calorie deficit will continue to pile up and make maintaining your deficit harder and harder until you either fix the problem or breakdown and give up.
The bigger your deficit and the longer you’ve been in it, the worse these effects will be. Here are the symptoms you need to look out for;
When eating in a calorie deficit your body adapts by down-regulating or reducing the production of certain hormones to help handle the increased demand placed on it.
Among these hormones is testosterone which is a big reason you have a sex drive in the first place. The longer you’re in a calorie deficit and the bigger the deficit it is the greater the effect on your testosterone.
Not to mention that when most people switch into a calorie deficit their intake of fat usually plummets as they try and cut back on calories which only serves to compound the problem because the fat in your diet helps with the production of testosterone and estrogen, the male and female sex hormones. (5)
If you’re suffering from low sex drive, then rest assured that once you come out of a calorie deficit then your hormone levels will be restored, and things will return to normal.
However, if you’re not done with your calorie deficit yet, then aim to get 30% of your daily calorie intake as fat to maintain your sex drive as best you can.
Perhaps the most difficult thing about dieting can be managing your hunger. This is only made more difficult the longer you’re in a calorie deficit and the greater this deficit is.
As we’ve already seen, eating in a calorie deficit decreases the production of Leptin and increases the production of Ghrelin which means you feel less satisfied after meals and hungrier pretty much all the time. (6, 7)
Yep, that’s right, eat too few calories for too long and you could stop losing weight. I know what you’re thinking, and no it’s not because of starvation mode or any other bullshit like that.
Instead, it’s the combined effect of not being as active (NEAT), the reduced calorie needs of your body and the reduction in metabolic rate (adaptive thermogenesis) that result in your calorie deficit slowly becoming your maintenance calories.
The outcome is your weight loss stops and because you’re eating such a low-calorie diet you’ll struggle to reduce your calories any further without compounding the problem.
If your diet is causing issues with the amount and the quality of sleep, this is a big warning sign you’re not eating enough and are in need of a change.
Poor sleep also impacts the regulation of Leptin and Ghrelin with researchers concluding that the “differences in leptin and ghrelin are likely to increase appetite”. (10)
Additionally, even a small amount of sleep restriction (11) can negatively affect your performance (12) which reduces your ability to maintain or build strength which is key to maintaining muscle as you lose fat.
Calories are your body’s source of energy and if you don’t eat enough, you’ll soon see your energy levels plummet and tiredness kick in.
This means not only will your workouts suffer but even doing your normal day to day tasks will become more difficult and cumbersome as you struggle to muster the energy you need. Activities, like climbing stairs and going for a walk, will leave you feeling out of breath and worn out.
This effect is regulated by the size of your calorie deficit with anyone on a very low-calorie diet feelings the effects more strongly and much quicker than those using a moderate or smaller deficit.
A common side effect of being in a calorie deficit even when it’s not a severe one is feeling cold a lot of the time. This is because your body needs a certain number of calories daily to maintain your core body temperature.
Research shows that those who consume fewer calories have a significantly lower core body temperature compared to those who weren’t eating in a calorie deficit. (13)
This is likely to be for several reasons;
Overall, the larger the calorie deficit the colder you’ll feel.
If you’ve been feeling irritable, moody and are finding that people generally want to spend less time with you, then chances are you’ve been dieting too hard and/or for too long.
Perhaps the most famous example of this is from the Minnesota Starvation experiment carried out during World war II. During the study, 36 men were put through a “grueling study meant to gain insight into the physical and psychological effects of semi-starvation and the problem of refeeding civilians who had been starved during the war.”
All of the participants were seen to develop irritability, moodiness and neurological deficits during the experiment. (15)
The last thing anyone wants to do when trying to lose fat is to also lose their muscle. However, eating too little calories when losing weight will result in just that. (16)
The key to successful weight loss is your ability to manage these side effects.
The first step to doing this is to ensure you’re not eating in a severe calorie deficit (anything over 500 calories below maintenance per day) as this is the fastest way to suffer.
Instead, choose a calorie deficit between 250 and 500 calories less than your maintenance and not only will you be able to consistently lose fat but the side effects will take longer to appear and be less severe.
Then when you do begin to suffer here are 2 strategies you can use to help reverse the side effects and come back to your calorie deficit with more energy and focus.
A refeed is a planned increase in calories used when dieting to negate some of the downsides of eating in a calorie deficit. It does this primarily but raising Leptin levels and giving you a mental break from dieting. (21)
Research shows that carbohydrates are superior to fat for raising Leptin levels which means you want to prioritise carbohydrate intake on your refeed days. This also has the added benefit of increasing your glycogen stores in your muscles and fuelling your workout performance. (22)
How often you should refeed is based on your current situation as the longer you’ve been dieting and the leaner you are the more likely you are to be suffering from the side effects of dieting;
As for what to eat when refeed you want to raise your calories to between your maintenance and 250 over with the following macros:
The alternative to refeeds is diet breaks. Diet breaks are typically periods of 7 – 14 days where you eat at maintenance calories.
The benefit of a diet break is a long period where you don’t eat in a calorie deficit which provides a larger relief from the negative side effects, both mental and physical, of being in a calorie deficit.
Depending on how ‘lean’ you are you will need to use diet breaks at varying intervals with a higher frequency the lower your body fat is;
As for what to eat when diet break, you want to raise your calories to between your maintenance with the following macros:
The amount of calories you need per day to maintain your weight varies from person to person and depends on several different factors including age, gender and how active you are.
Most people will be able to lose weight with a calorie deficit of around 500 calories under maintenance per day. In fact, anything up to 750 calories below maintenance is considered normal and acceptable for most people.
However, when you go beyond this point is when you start running into trouble and if you’re eating as little as 1,000 calories or less per day you are considered to be eating a very low-calorie diet.
Not only this but it makes weight loss hugely unsustainable and your chances of successful fat loss incredibly low.
To avoid the more serious side effects of dieting you want to maintain a calorie deficit of about 500 calories under maintenance as this will allow you to lose weight and better manage the side effects of dieting.
You also want to be aware of the metabolic changes that occur during weight loss and the side effects this can produce. You can then use refeed days and diet breaks to help manage these side effects and continue losing weight.