When both males and females embark on a fat loss journey, the first thing that comes to mind is to neglect the long term and instead focus on hard and fast results. As a result, most dieters will place themselves on an incredibly low intake. For females this always means going straight to 1200 calories, while males always seem to sit around the 1700 calorie mark. In this article, we’ll examine the downsides of a low caloric intake showing why it's not the way to go from both a physiological and psychological perspective, as supported by science and our own experience.
One of the first studies that caused alarming discussion surrounding low-calorie diets was the Minnesota Starvation Diet. This human experiment in the 1940s was designed to determine the physical and mental effects of severe and prolonged dietary restriction and the effectiveness of dietary rehabilitation strategies. 36 healthy young men were put through 4 phases of dieting from a controlled period, followed by a semi-starvation of around 1600 calories a day (a significant calorie deficit), then a restricted period and finally unrestricted post-diet.
The study showed that there were both significant physical and psychological repercussions that came from the lengthy dietary restriction. These included hysteria, depression, and hypochondria, as well as a preoccupation with food, hoarding food, loss of sexual drive, anger, decreased social interests, and lower leg edema due to the increased water intake in aim to rid them of hunger feelings(1)(2).
The men became incredibly obsessed with food with recordings of participants staying up till 5am studying food recipes, some took up smoking, others began stealing and some chewed up to 20 packs of gum a day until the laboratory banned it. All in all, a severed relationship with food resulted. Physically, the subjects metabolic rate decreased indicated by a drop in body temperature and heart rate, suggesting that their Basal Metabolic Rate (the energy burnt by your body when you are at rest) had fallen. Although the conditions of this experiment were extreme, it is certainly a sound indication of the possible effects of prolonged dieting on extremely low calories.
So what are the dangers of dieting on too low of an intake?
1. Metabolic Effects
Your body learns to do more on less fuel. What does this mean for fat loss? It slows right down! Every person has a ‘body-fat set point’ which is the body-fat level our body is accustomed to and will attempt to maintain itself. It's highly individual and a number of people can have varying set points subject to differing factors. This ‘set point’ is based on a range of factors including genetics, activity level, and nutritional habits over the course of their lifetime. Whatever that set point is, the body wants to keep you there as long as it possibly can.
If you drop your caloric intake too quickly or diet on a low caloric intake, the body will adapt to make fat loss more difficult. These adaptations are made through changes in your metabolism. This is why fat loss is faster at the beginning of a diet, however it isn’t long before your body responds by making it a little harder for you to burn calories and shed the rest of the undesired fat. This is due to the further you get below your set point, the more efficient your body's energy systems become(3).
Your cellular energy systems become able to generate more power or more mileage, from less fuel. So you become like a super-efficient hybrid vehicle which in this case, isn’t ideal(4). Your basal metabolic rate lowers and the amount of energy you expend during activity is reduced, and even how much your body burns breaking down food (thermogenic effect of food) and nutrients decreases(5)(6). So as you get further below this set point, your body becomes more and more efficient. Your fat cells shrink, and in the process, they excrete smaller amounts of leptin which (amongst other things) tells you when you're full(7).
Interestingly, studies have shown that your levels can drop far more than they should, based on the amount of fat you lose, and they stay low even after your weight has stabilised(8). Basically, your body overdoes it, so you rarely feel full or satisfied. At the same time that this fullness hormone is decreasing, ghrelin, the hunger hormone, is increasing(9). So you’re hungrier, less satisfied and are burning fewer calories. This is why a lot of people suffer with ineffective results and/or blowouts and overeating.
2. Weight Regain
After dieting for a period of time, your metabolism adjusts to a lower caloric intake. This means that when you resume your normal eating, you can potentially gain back all the weight you've lost, and sometimes even more.
Overshooting is used to describe the weight gained after prolonged rigorous dieting. While this ‘fat overshooting’ may not seem just or fair given the hard work exerted into all those years of dieting, it’s essentially like an evolutionary survival mechanism. Usually when a diet is ‘over’ - whether that means giving up or having achieved your weight goal, the individual is left with a repressed metabolic rate, and an overwhelming desire to eat. This combination can result in huge, compensatory caloric intakes that lead to rapid fat gain.
The body is equipped with defensive reactions to a negative energy balance (calorie deficit) and can restore weight lost, ‘beyond the point of weight restoration’. In other words, there’s a high potential to regain the weight that you lost, and then some. So after you’ve lost weight and sit at your goal body, many of the metabolic adaptations made while in a calorie deficit persist while you aim to maintain your new body weight(10)(11).
This is why rebounds can often occur in conjunction with an increased hunger rate. So restraint and a conscious reverse diet must be practised post-dieting to avoid adverse effects, otherwise rapid weight regain will occur. Research has shown that weight gained during this ‘aftermath’ period is stored as fat(12) in conjunction with the susceptibility of adipocyte hyperplasia which is the addition of new fat cells(13) which can facilitate the fat overshooting.
3. Binge eating and/or a poor relationship with food
Fewer calories facilitates hunger and dissatisfaction after meals which can lead to blowouts and binge eating. Dieting on a very low caloric intake is often the reason for binge eating episodes and a poor relationship with food. Many people who experience binge eating will do so due to the restrictive practice that places them in a ‘ticking time bomb’ scenario unable to sustain the low calories and rigid dieting. When you take the feeling of hunger and put it in the context of prolonged deprivation it only seems natural that anyone who is dieting in these circumstances will eventually surrender to the temptation and satisfy cravings or disregard strict portion control.
4. Nil energy for training
Less fuel can leave you feeling tired and fatigued, providing no energy for training and physical activity. On fewer calories, you'll have less energy throughout the day which particularly affects training performance as well as strength. Food is fuel and without it, it makes sense as to why your alertness and motivation for physical exertion can dwindle throughout the day.
From a calories in vs calories out perspective, giving yourself additional intake can make for a greater caloric burn throughout the day through increased performance and activeness as opposed to great calorie restriction which instead can have you opting for the couch, missing session and feeling sluggish. On low calories, not only does your energy decrease during sessions but so too does your NEAT (Non-Exercise-Activity-Thermogenesis). Generally, a lower calorie intake makes for a lesser tendency to be 1) active and 2) opt for the more energy required movements; instead reducing energy expenditure is usually prioritised in remaining less active.
5. Inability to be flexible
Fewer calories gives less room to incorporate more desirable foods and instead restricts food choice. On low calories there is quite often a restriction in choice of food, which makes for fitting in foods that are novelty or eating out increasingly difficult. Again with this additional restriction, it can interfere with adherence due to facilitating blowouts and ‘throwing in the towel’ moments. On a higher caloric intake, it can make for the possibility of consuming lighter but satisfying meals throughout the day and saving a heartier allowance for a dine-out meal or high-calorie food of choice within the intake goals.
6. Muscle loss
Low calories can cause muscle loss which isn’t favourable for metabolic capacity. Low-calorie diets have a tendency to deprive the body of essential macronutrients for maintaining muscle mass. A significant amount of early weight loss on a low-calorie diet is water weight, and later weight loss includes approximately 30% muscle loss or more(14). This isn’t ideal given that muscle tissue is about 8 times more metabolically demanding than fat. What that means is a higher percentage of lean body weight (muscle) results in a higher metabolism compared to individuals of the same weight with a lower percentage(15). Moreover those with a higher lean muscle mass will also burn more while resting.
An example of our success WITHOUT low-calorie dieting:
Roxy came to us on the far left on low calories and binge eating multiple times a week. We then began her on a higher caloric intake that was only a slight deficit to her TDEE (Total Daily Energy Expenditure) and throughout her 10kg fat loss never went below a 1600 calorie intake despite her aesthetic goal to compete in a bikini modelling show in optimum condition.
Roxy's success transitioning out of low-calorie dieting
For those who don't know our beautiful athlete Roxy, Roxy has had great success as a fitness model coming from an array of all different approaches to prep. Roxy at 24 years old was mature and passionate enough about her sport to realise she wanted to explore a range of approaches before settling on what would deliver the best result in both the on and off-season. What a lot of people fail to acknowledge with competitive athletes is the importance of maintaining conditioning in an off-season not only for personal confidence and quality of life, but also for the benefit of the upcoming season too. This is where Roxy found flaws in her previous experience with clean eating and significantly reducing caloric intake. Coming from a flexible dieting background maintaining her comp conditioning without fat gain and reaching 2200 calories, Roxy was impacted greatly by the restriction of lower calories which brought to fruition an underlying binge eating disorder that she'd successfully managed previously with flexible dieting.
So, where did we come in?
We'd previously coached Roxy throughout her reverse from an International Fitness and Bodybuilding (IFBB) show according to a flexible dieting approach. 6 months ago Roxy came back to us after experiencing a rebound post dieting quite rigidly for an IFBB show. She had gained some weight on the scales and wasn't happy aesthetically with the result of what was a vicious cycle of low-calorie dieting followed with quite substantial binges. Her ultimate goal was to just get the 'unhappy weight' off in time but ultimately stop the binges and build a better relationship with food flexibly again.
What did we do?
Roxy was on an array of intakes that were very low for her size and activity level and restrictive. With that, she was binging around 3+ times a week stemming from the restriction and poor relationship with food developed from those low days. We immediately bumped her intake up just slightly below maintenance. The aim here was to reduce the binges but not be in too much of a deficit so that fat loss was unmanageable.
What was the result?
Roxy reduced her binges over a few months from multiple times per week to almost non-existent. Where she might have exceeded calorie targets during recovery was tracked for accountability and less severe than previous episodes. As her body fat dropped and she became physically in shape and mentally stronger, Roxy decided she'd like to prep again for a new goal of stepping on the World beauty Fitness Fashion (WBFF) stage. With mindful consideration of her mental state, adherence and relationship with food we decided on a slow, long and less aggressive prep over around 16 weeks. In this time Roxy never went below 1600 calories and only experienced 3 calorie decreases based on her progress. She will now reverse diet with the aim of maintaining as close as possible the conditioning she has now while reaching a little over 2200 calories.
Low-calorie dieting is just a TOUGH MEANS to the SAME end
In a recent study, researchers put 25 participants on a five-week very-low-calorie diet and another 22 volunteers went on a 12-week low-calorie diet with a 750 calorie difference between the two groups. Investigators found that right after the end of their diets, both groups had similar levels of weight loss. The average weight loss was a little over 19 pounds among those on the very-low-calorie diet and just under 19 pounds among those on the low-calorie diet. However, participants on the very-low-calorie diet had lost about 3.5 pounds of fat-free mass, compared with 1.3 pounds among those on the low-calorie diet. Fat-free mass accounted for 18 percent of weight loss in the very-low-calorie diet group and 7.7 percent of weight loss in the low-calorie diet group, the study found. This goes to show the slower pace the body can produce fat loss results at as well as the detriment to muscle mass of very low-calorie diets.
Low-calorie dieting is not only inadequate for weight loss in that it comes with strategy concerns as to what measures will be taken once metabolic adjustment occurs and as well as this is also ineffective for adherence and detrimental to your health and lifestyle. For optimum fat loss results to your body’s requirements without low calorie or adverse practices enquire about our customised nutrition for body transformation success today.
1. Troscianko, Emily. “Starvation study shows that recovery from anorexia is possible only by regaining weight.” (2010). Retrieved on April 13, 2014.
3. MacLean, P. S., Bergouignan, A., Cornier, M. A., & Jackman, M. R. (2011). Biology's response to dieting: the impetus for weight regain. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 301(3), R581-R600.
5. Miles, C. W., Wong, N. P., Rumpler, W. V., & Conway, J. (1993). Effect of circadian variation in energy expenditure, within-subject variation and weight reduction on thermic effect of food. European Journal of Clinical Nutrition, 47(4), 274-284
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7. Löfgren, P., Hoffstedt, J., Näslund, E., Wiren, M., & Arner, P. (2005). Prospective and controlled studies of the actions of insulin and catecholamine in fat cells of obese women following weight reduction. Diabetologia, 48(11), 2334-2342.
8. MacLean, P. S., Bergouignan, A., Cornier, M. A., & Jackman, M. R. (2011). Biology's response to dieting: the impetus for weight regain. American Journal of Physiology-Regulatory, Integrative and Comparative Physiology, 301(3), R581-R600.
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13. Jackman MR, Steig A, Higgins JA, Johnson GC, Fleming-Elder BK, Bessesen DH, and MacLean PS. Weight regain after sustained weight reduction is accompanied by suppressed oxidation of dietary fat and adipocyte hyperplasia. American journal of physiology Regulatory, integrative and comparative physiology 294: R1117-1129, 2008.