Severe Calorie Deficits for extended periods of time
What is considered a large/severe calorie deficit? It is generally when you go 25% or more below your daily maintenance requirements.
Maintenance calories – the daily energy intake to maintain current bodyweight
Most people today, including me, are guilty of going for the ‘more must be better’ approach, such as reading that 1 scoop = 1 serving on supplements, then taking a double scoop, reasoning that it means double the gains!! The same goes when people are calculating their macros and calories to start fat loss.
The macros calculator says you should have a 300 calorie deficit below maintenance in order to start losing weight, however, many of us think that by making it a 700 calorie deficit, we’ll lose even more fat, meaning QUICKER GAINS!
We all want quick “gains” from complete beginners to even experienced dieters, we all want to go from porky to sculpted in some super silly time frame, usually a month or two. But we need to remember nutrition and dieting is a trial and error process, slow and steady wins the race.
When you try and shoot off like the hare, yes you will drop fat quicker, with almost immediate results and gratification. This can be a benefit in the early stages of a diet, improving your motivation since you can see it’s working. BUT like most things it comes with a cost and many detrimental effects such as abnormal hormone fluctuations (including thyroid and testosterone), fogginess and memory dysfunction, trouble concentrating, decreased metabolism, reproductive dysfunction (loss of menstrual periods, infertility), depression, anxiety, and sleep disruption.
Here are the 3 main effects of severe calorie deficits:
Increased muscle loss is a real probability with larger calorie deficits, especially in people who are already lean and have little fat to lose. We don’t want to lose muscle tissue as it is metabolically active, which means it burns calories while you’re resting. It also protects joints and internal organs.
Why does the body eat muscle when it has fat to burn? Now that you are in a large calorie deficit and starving, your body will decide it needs to start reducing calorie outgoings by getting rid of tissue.
1lb of muscle generally burns 6-10 calories per day, while 1lb of fat generally burns 2-4 calories per day. So what is the body going to choose? Muscle, of course! By reducing its muscle tissues, the body is slowly lowering its RMR – Resting Metabolic Rate. The body is lowering your total calorie outgoings to try and match the severe calorie deficit.
Burning all this muscle means that starving ourselves leads to more body fat—not less—over the long term. As soon as we stop starving ourselves, we have all the calories we used to have but now we need less of them, thanks to all that missing muscle and our slowed-down metabolism. Now our metabolism sees eating a normal amount as overeating and creates new body fat.
Increased demands on will power and determination to maintain the diet. Extreme deprivation is usually too much to handle for the majority of us. As we already have many external stresses in our lives like work, school, family life, money, a large calorie deficit can be an additional factor. There are many side effects to a build up of stress:
Psychological effects – Anxiety, depression, mood swings, hyper sensitivity
Behavioural effects – overeating, quickness to argue, poor job performance, decreased relationships with friends and family.
This stress can quickly lead to binge eating! Increased stress and hunger deprivation (especially long term) will lead to going off track, resorting back to your normal diet, which wasn’t working in the first place.
Loss of energy. As your metabolism lowers so will your energy levels, meaning the body no longer has the necessary calories to function. It has to make adjustments that can lead to decreased brain function due to lack of fuel, tiredness due to poor quality of sleep and recovery, which meaning daily tasks become harder.
So…. the reality is that large calorie deficits can work in the short-term, but the risks involved far outweigh any possible benefits, and it is ultimately an unhealthy approach. Loss of muscle and energy, with extra stress, leads to the inevitable binge and yo-yo dieting that can in fact increase fat levels. The best option then, is to select a more moderate deficit, allowing your body to adapt, and fat loss to continue over a longer period.