Have you ever found that you can’t seem to lose weight as easily as you used to or that your weight loss comes to a halt even though you’re in a calorie deficit? Read on to see how diets are failing us.

Common misconceptions when referring to weight loss and plateaus are “metabolic damage” and “starvation mode”. They are notions that are not true. When something is damaged, it implies that it is broken or beyond repair. People will believe they can’t lose weight, no matter how fewer calories consumed or how much activity performed because either one of these phenomenon occurs.

Studies on starvation show that everyone will lose weight if we create a calorie deficit (Müller et al., 2015). What is happening in your body is that your metabolism is adapting to the calories you’re consuming. It has created new maintenance. 

No matter how low your calorie intake is and how much exercise you perform, your metabolism will not become damaged. What does happen during dieting and weight loss is a sensation referred to as metabolic adaptation.


When we refer to our metabolism, we tend to look at it as a whole. However, different factors contribute to your metabolic rate. 

Basal Metabolic rate BMR:  The minimum calorie requirement your body needs to maintain life in a resting state.

Non-exercise activity thermogenesis NEAT: Is the activity that isn’t intentional exercise. Fidgeting, walking, taking the stairs, cleaning, playing with the kids, walking the dog and gardening.

Exercise activity thermogenesis EAT: Intentional exercise. Depending on the type of training you perform, this will differ in the number of calories burnt.

Thermic Effect of food TEF: Thermic effect of food is the number of calories you burn digesting food.

Total daily energy expenditure TDEE: The number of calories that your body will burn is a 24hr period. 

Fat loss will affect these to some degree. BMR will decrease due to being smaller and therefore requiring less energy. NEAT activity decreases over the time of being in a deficit. Due to a reduction in energy and feeling lethargic. Your TEF will fall due to eating less, and your EAT will reduce again because a smaller body will use less energy than a larger one. Therefore, your TDEE will decrease due to fat loss.


Metabolic adaptation. 

Metabolic adaptation is our bodies biological response to fight back against weight loss.

Weight loss happens when we eat fewer calories than we burn, creating a negative energy balance.

Our bodies have a self-regulatory system that causes the metabolism to slow down to meet our new energy supply. Our body’s goal is to maintain a stable environment where it has enough energy to perform daily tasks and keep us alive. It’s good to know that our bodies are capable of doing this, but it can get in the way when we are trying to lose weight. 

Our bodies will promote fat storage and oppose fat loss. We store fat easily for times of starvation, so we can have energy stored. And our metabolisms are equipped to slow down to preserve energy and become more efficient at utilising it. But in today’s era of sedentary lifestyles and easy access to foods, the famine is not coming. 

However, we can trick our bodies into thinking this is occurring by creating an imbalance in energy. By reducing the number of calories, we consume and increasing activity. The mistake often made when doing this is that people will go on a crash or restrictive diet, usually consuming minimal calories and performing too much movement (generally in the form of cardio). What’s the point in slow weight loss on a small deficit if we can see quick weight loss on a large deficit?

Weight loss is not a linear continuous but ends when the curve flattens. Which means we have established a new balance between energy uptake and energy expenditure. Most women will diet at around 1200 calories. So, when metabolic adaptation occurs, they must go lower with their calories or increase activity levels to create another energy imbalance. Dropping from 1200 calories down to 1000 calories will only see your metabolism continue to adapt to the stimulus. However, our hunger sensation will increase, setting us up for post-starvation obesity (more on that below).

Our metabolisms are also dependent on our body composition. Body composition consists of two components (see image below). Lean body mass results in a faster metabolism. When we diet, especially on low calories, we lose muscle and other lean body mass. Reducing our energy needs and slowing our metabolisms slightly. 

Some people’s bodies are more efficient than others. For some metabolic adaptation kicks in much earlier on in dieting than others. Metabolic adaptation explains why weight loss plateaus are so common. 


Why do diets become less effective as time goes on?

If fat loss is as simple as calories in vs calories out, which calories do matter and creating a deficit is the key to losing body fat, then why doesn’t this approach work or why is it working less as we do it more overtime? 

Our metabolism isn’t a muscle that we can see; it is made up of hormones and plays a role in many processes. We are hard-wired for stress and survival.

Dieting is otherwise known as a controlled method of starvation; your body’s natural response is to go into defence. Dieting is a significant stress on the body if done for too long and too aggressively. The more we diet, the better our metabolisms become at being resistant to the effects of yo-yo dieting. And can adapt quicker to lower calories. Which is why we find it harder to lose weight the older we get or after dieting for a prolonged period.

If we believe we create a deficit of 500 calories, your metabolism can adapt to this very quickly and become efficient at utilising this energy quicker than it did before. Meaning all your physical energy transferring activities will slow down, tipping the energy imbalance scales back to even. The 500-calorie deficit now doesn’t exist, resulting in a weight loss plateau.

So, the more prolonged we are in a deficit and the number of times we diet makes weight loss and dieting harder to achieve as time goes on.

Weight gain post-diet.

Metabolic adaptation plus an increase in hunger when dieting sets us up for weight gain post-diet. A study has shown that lowered metabolism can persist long after the diet has ended (Fothergill et al., 2016).

Weight gain post diet is otherwise known as post starvation obesity. After a period of restrictive eating on low calories, your hunger levels will increase, and you’ll experience over-eating. It is a part of the auto-regulation process attempting to restore body fat (Dulloo, Jacquet and Girardier, 1997).

Metabolic damage does not exist; however, metabolic adaptation does during weight loss and sets us up for post starvation obesity. Remember, our bodies are programmed to store fat and resist fat loss. We live in an environment where food is in abundance and extremely accessible. It is effortless to over-consume calories in a short period—resulting in rapid weight gain. 

Although this may sound like successful weight loss and maintenance is non-achievable, however, this isn’t the case. There are strategies that you can put in place to minimise the risk of metabolic adaptation occurring and avoid post starvation obesity. Click here to read how to combat metabolic adaptation and maintain your weight loss results.



Dulloo, A., Jacquet, J. and Girardier, L., 1997. Post Starvation hyperphagia and body fat overshooting in humans: a role for feedback signals from lean and fat tissues. The American Journal of Clinical Nutrition, 65(3), pp.717-723.

Fothergill, E., Guo, J., Howard, L., Kerns, J., Knuth, N., Brychta, R., Chen, K., Skarulis, M., Walter, M., Walter, P. and Hall, K., 2016. Persistent metabolic adaptation 6 years after “The Biggest Loser” competition. Obesity, 24(8), pp.1612-1619.

Müller, M., Enderle, J., Pourhassan, M., Braun, W., Eggeling, B., Lagerpusch, M., Glüer, C., Kehayias, J., Kiosz, D. and Bosy-Westphal, A., 2015. Metabolic adaptation to caloric restriction and subsequent refeeding: the Minnesota Starvation Experiment revisited. The American Journal of Clinical Nutrition, 102(4), pp.807-819.