*For context, this article is aimed at the typical body conscious gym goer who is always on a diet but never gets the results they are looking for*
One day highly restrictive 1,200kcal diets will die and so too will juice cleanses, shake diets and any form of starvation diet. Why? Because they suck arse and could damage your health, and not just your physical health but your mental health too.
Don’t get me wrong you WILL lose weight on a very low-Calorie diet, that’s basic physics. It’s all maths. If you put less energy into your body than your body needs to function the energy you have stored in your liver and muscles (Glycogen) will deplete quickly. During periods of very low energy intake, such as these silly 1,200kcal crash diets that every commercial gym seems to advocate in January rapid weight loss occurs but the majority of that comes from water and muscle, this results in a loss of lean mass and that means that your resting metabolism reduces. Lean mass, for the record, is your muscles and your bone minerals, so eating a low energy diet can also damage your bone density. You see, for every 1g of stored glycogen you also store around 3g of water - this is one reason why very low carb diets produce rapid weight loss, because you are depleting carb and water stores. After the body has depleted itself of Glycogen you have to get your energy from somewhere, so your body starts to catabolise (catabolism is basically your body eating itself) muscle in order to break down and metabolise amino acids for fuel and THEN your adipose tissue will get catabolised last. Yes you will lose fat, but unless you are extremely overweight and have LOTS of body fat to lose, very low Calorie diets are not the healthiest or most sustainable way to do it. You do, after-all want the majority of the weight you lose to be fat and not lean body mass like muscle.
Your resting metabolism is body mass + activity. When you lose weight quickly your body mass reduces but, importantly you lose muscle which means that your Resting Metabolic Rate (RMR) is lower. Therefore, when you hit your target weight and then go back to eating the way you used to not only has your resting metabolism reduced, but even with extra activity, so too has your overall maintenance Calorie level. This is part of the reason why weight rebound after crash diets is common. Although the often quoted 95% rate of weight rebound that seems to have become nutritional lore has no statistical basis to it. But, looking at Weight Watchers as an example we can see that most participants regain weight over the 5 years after completion with more than 80% failing to maintain their target weight (1). Slimming clubs are happy about this, by the way. That's their business model without weight regain their business would fail. They NEED you to put the weight back on, they RELY on your repeat business... Yep, that's disturbingly unethical.
So what can you do to reduce the reduction in lean body mass (LM)? Resistance training is one way to slow the reduction of LM which is why weight training is so often recommended for people trying to achieve fat loss. Higher protein intakes are also necessary to stimulate muscle protein synthesis and ameliorate catabolism, but if your calorie intake is really low this is hard to achieve, unless you are morbidly obese, which means a BMI above 30 and a waist circumference above 80cm (31.5") for a female or 94cm (37") for a male.
Using myself as an example to illustrate RMR I weigh 75kg and a quick Calorie equation tells me that my RMR is 1,800kcals. So, if I were to put myself on a 1,200kcal diet I would be eating 600kcals below my basal rate of energy requirement. If I kept this up for a few days I would definitely lose weight. But if I kept it up for any length of time I would experience some interesting adaptations. To work out your RMR you can download any number of Calorie calculators from your app store, you can just use this simple equation: bodyweight in KG x 22(F) or 24(M). Or you can use this rather nifty tool from Awesome Supplements:
Metabolic ‘damage’ isn’t a thing, you can’t permanently break your metabolism through dieting. There are medical conditions which can affect this, which you would almost certainly be aware of by now. But there is something known as metabolic adaptation (3). Which is a reduction in BMR, but this is unlikely and would require metabolic testing to confirm.
Energy restriction is accompanied by changes in circulating hormones, mitochondrial efficiency, and energy expenditure that serve to minimize the energy deficit, attenuate weight loss, and promote weight regain. - Trexler et al. 2014
But there is also Adaptive Thermogenesis. This is when your energy output reduces to match your energy input. In other words, if I was to continue to exercise at my usual rate (remember my RMR is 1,800kcals but including activity my total daily energy expenditure (TDEE) over 2,700kcals per day) while only consuming 1,200kcals my body would slow down to match the energy available to it. You may not even notice this but, trust me, you will slow down. Does that make sense?
This is a common problem I have seen with online fat loss clients and personal training clients. Being on several online forums for fitness and nutrition I see a lot of very active and healthy weight people stressing about scale weight and often ask questions which usually go something like this:
“Help, I have been eating 1,200kcals for 6-months, I try to do 8-10,000 steps per day and do weights 3x per week, HIIT every morning and Park Run on Saturdays. I’m not losing weight and find it really hard not to binge at weekends and constantly obsess about carbohydrates.”
Here’s why; forcing your body to perform at such a high level while not providing it with the energy it needs to do this will negatively affect hormone balance, as quoted above. Your body will slow down, meaning that you will fidget less and move less in general. You’ll find yourself taking the lift instead of the stairs, sitting instead of standing, you'll even blink less and speak slower or more quietly! You might not even notice this, it’s usually a subconscious decision. Not only this but you’ll be knackered all the time, your joints will probably hurt because your body is under recovered and your sleep has probably become something that other people experience. This means that you’ll skip the gym more and more frequently and when you do train, because you are so under nourished and so low on energy your workouts will suck. They’ll feel hard, your rate of perceived exertion will be greatly increased so you will feel like you are exercising with more intensity than you actually are. If you are lifting weights, you’ll find the numbers on the bar going down, or at least not going up as they should be. If you do endurance exercise, you’ll find it much harder to go further for longer and you won't be getting any KOMs or QOMs on Strava. Your sleep is probably affected, your mood will definitely be affected and, your self-discipline and levels of motivation will go way down. The reason you crave carbs and binge at weekends is because you’re fucking shattered and your body needs energy, not to mention the stress you are putting yourself under. If this was me (in the example I have given so far) my TDEE should be 2,700kcals but while eating 1,200kcals my non-exercise activity and exercise output will drop down until my actual TDEE is much closer to that 1,200kcal intake. Any weight loss would slow down and eventually stall because the size of the energy deficit is now much smaller, and then where do I go from there? Drop my kcals even lower?
As I’ve already mentioned large deficits do work and you WILL lose weight quickly. But they aren’t long-term sustainable. A 2017 study looked into this to see which would be the most effective (2). A rapid weight loss “crash diet” versus a slow weight loss diet. The rapid group lost weight over 5 weeks while the slow group lost weight over 15 weeks. Both groups lost about the same amount of weight and saw similar reductions in Anthropometric readings, but the slow group maintained better body composition, with the fast group losing more of their body weight from lean mass.
Couple this with the fact that a very low energy intake also means a very low nutrient intake and it’s not uncommon to develop nutritional deficiencies which can have, in some cases, quite serious health implications.
The benefit to seeing rapid weight loss is that you can feel motivated by these early results and be encouraged to keep going (4). A morbidly obese person has an awful lot of excess energy stored up in all that adipose tissue which means their body is basically built for starvation. This means that obese people may well benefit from a month or two of very low-Calorie dieting followed by a period of slightly higher kcal dieting to avoid some of the negatives associated with rapid weight loss. This means a structured plan, education around energy balance, nutrition, food environment, food choices, time management and a whole plethora of other practical stuff.
Indeed the now famous Newcastle Diet study (5) put obese patients (BMIs ranged from 32 to 45) with type 2 diabetes on a 600kcal per day liquid diet. They lost significant amounts of weight and improved health markers, including reversal of T2D. But, this is very obese, very sick people who were undergoing clinical supervision. This approach isn't suitable to the typical. otherwise healthy gym going person who wants to get back into their jeans. And no, Juice Plus is NOT a clinical intervention, it's fucking pyramid scheme!
So, from a health standpoint (unless you have a BMI of around 35-40) slow and sustainable is better but requires more effort and more lifestyle changes, but that’s the whole point isn’t it? In order to become a better version of you, you have to cultivate better habits.
If you have found yourself in the loop of dieting too low and are now feeling trapped by your diet what should you do? You need to change your mindset, you can’t diet forever and at some point, you need an exit strategy, you need to learn how to eat to maintenance so that you can lead a functional life, have more flexibility around food but be able to do so without feeling anxious or guilty. Living your life being a slave to your own restrictive mindset and never really being able to enjoy your food or your workouts could mean that you are on the verge of developing an eating disorder.
The simple answer is to bring your kcals back up to maintenance. You will gain a little weight initially, but this will mostly be a combination of extra food matter in your bowels combined with more Glycogen and water in your cells. Scale weight doesn’t always equal body fat! This is what we now refer to as a diet break (6). If you are dieting long-term scheduling regular diet breaks is a really good idea. It could be every other month, one week in six or simply to coincide with social events like birthdays and holidays. It still requires a mindset shift because you need to shift from an attitude of lack and self-restriction to one of health and happiness. This is probably a blog in itself though, so I'll return to this concept in more detail another time.
If you have been dieting low and got to very low levels of body fat, as with physique competitors, then your body will prioritise fat storage as you gain weight, but that's probably not a bad thing, it just means that you're going from abnormal to normal (6). Very low body fat is not healthy, it's kinda ironic that when physique competitors step on stage looking their best, they are at their least healthy from an endocrine point of view. This is especially harmful for women and many bikini models lose their periods, some never get them back!
One strategy that physique competitors employ post comp is 'reverse dieting' to increase their kcals by about 200-400 (or any number that makes mathematical sense in their situation) per day. By this, I mean their daily average for that week. It can help to minimize the amount of fat gain and also emphasises the discipline to not binge after such a long period of self-restriction. Reverse dieting was popularised by Dr Layne Norton and is still a somewhat controversial concept that a lot of researchers and practitioners disagree with. I'm personally not a fan, but then most of my clients don't enter bodybuilding contests and it simply isn't necessary for them.
However, using myself as an example (but, as I have already said, you don't NEED to do it slowly. Here’s how this reverse diet approach might look if I were a physique competitor:
Week 1: 1,200kcals per day
Week 2: 1,700kcals per day
Week 3: 2,200kcals per day
Week 4: 2,700kcals per day
You get the picture, right? What will this do for you? It’s not so much that eating more food makes you burn fat, not directly – you still need to be in an energy deficit to achieve this – but as your energy intake starts to get closer to your energy output your body will respond positively. (3,6).
However, as I have stated, this is one strategy sometimes used by physique competitors, I'm willing to bet that's not you. So what should you, a recreationally active person who simply wants to shed a few pounds do? What I would urge you to do ideally if you have been dieting low for a while is to employ the previously mentioned diet break. Just bring your kcals up to maintenance and then stay there for a month or two. Learn to eat to maintenance, enjoy your training, enjoy the mental clarity and the emotional parity that comes with being adequately nourished and not feeling the need to binge because you are now fuelling your body adequately.
During this time, you will secrete less stress hormones, your appetite hormones Leptin and Ghrelin will balance out. Your mitochondrial efficiency will improve, meaning that your body produces more ATP and increases your thermic output (Calorie burn). Muscle contraction will happen more rapidly, you’ll fidget more, you’ll start taking the stairs two at a time, your workouts will feel much better because your muscles recover quicker and the numbers on the bar will start to increase again. As your body starts to move more the energy deficit you eradicated by having such a low-Calorie intake will increase automatically. For clarity, when you eat correctly and train consistently and progressively (and by train I mean resistance training) you can create, what is often called body recomposition. This is when some of the energy used to create the adaptations to exercise is drawn from fat stores, because your high protein diet and resistance training is adequately feeding your muscles. What most people mean when they say they want to 'tone up' is to lose fat and build muscle. With body re-comp you rarely see much change in scale weight but your see physical changes in your body. Women drop dress sizes without losing weight. You feel stronger, fitter and more self-confident. You enjoy your food and never feel restricted. Your focus shifts from scale weight to weight on the bar or other performance goals, it feels liberating and motivating and you actually ENJOY your training.
But, after you have been on maintenance for a while, if your goal is still to lose some body fat just create a smaller deficit of around 15-20% of maintenance moving forward. The smaller deficit is more sustainable and means that you still have the energy to train hard and, more importantly, recover between workouts. Refer to the following infographic for an example of how you might work out your numbers.
I always encourage clients to focus on performance more than body weight. Setting your goals and your sense of worth solely on what the scales tell you is a slippery slope to mental illness for some people. But, if you set yourself performance goals and eat in accordance with the training load for that goal it’s a lot more motivating. This, of course, means a change in lifestyle but that’s a good thing. Be the best performing version of yourself, aim for optimal health, rather than being stressed out and having a disordered and obsessive attitude to food that constantly makes you feel under pressure. Life is too short to waste it berating yourself. I feel the Bobby McFerrin song (80s nostalgia alert) is quite apt here; "Don't Worry be Happy" and happiness is a loaded barbell (or cast iron kettlebell).
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