Is my metabolism broken?

Understandably, many of us feel that our metabolisms are seriously damaged and it has become impossible to lose weight.

After a lifetime of dieting, it can feel like no matter what we try, we simply can’t drop the pounds.

Calorie balance is confusing because it is not always as simple as it seems. As adaptations happen in our body, it can seem like our body is not obeying the laws of physics, but this is a dangerous line of thinking that can lead to extreme or false measures and a mindset that becomes open to seemingly exciting marketing messages that are infused with nonsense.

Regardless of how often you have dieted you will not circumvent thermodynamics and no amount of magic avocados or juice cleanses can change this. Any avoidable adaptations your body has made will be predictable, fixable and not particularly extreme.

Rather than reaching the understandable but false conclusion that our body doesn’t work, it is better to understand our body and how it works, so we can make changes accordingly and in line with our personal goals.

Regardless of how effectively and slowly you lose weight there will be:

  1. Unavoidable slowing adaptations to your resting metabolic rate (a smaller object requires less energy to survive)
  2. A reduction in the amount of calories you burn during exercise (a smaller object requires less energy to be used)

Therefore, if you start losing weight at 1800 calories and  lose 20 lbs, you will probably need to reduce your calories to continue losing weight. This is not indicative of a damaged metabolism, this is indicative of success.

A slower metabolism is an inevitable side effect of weighing less, but chronic dieting can also cause additional processes to change in your body. Making weight loss even harder:

1.Thermic effect of eating goes down when you eat less for prolonged periods of time.

The body will spend less energy on digestion when it doesn’t have sufficient calories.

  1. Non-exercise activity thermogenesis adapts down when calories are permanently low.

Our body is a complex machine. With less calories to ‘waste’ your body will stop ‘wanting’ to move.

  1. Calories absorbed increases –  you absorb more of the calories you eat.

Calorie absorption will increase when you are in a permanent calorie deficit. This may mean that where you were absorbing 1500 per 2000 calories consumed before reducing calories, your body may now be absorbing 1800 per 2000 calories consumed.

What does all this mean?

Your body is certainly not broken.

It uses less energy to digest food because it is reluctant to waste calories. It is hesitant to ‘move more’ because it doesn’t want to burn and ‘waste’ calories and it is absorbing a higher percentage of the food you consume because it doesn’t want to ‘waste’ calories.

Some people call this ‘starvation mode’ when in reality it is just the body being understandably more prudent with calorie usage and expenditure when there are less calories available.


Let’s compare two people that weigh 200 lbs to illustrate what dieting can do:

Person 1 – always weighed 200 lbs Person 2 – Dieted down from 250 lbs
Weight 200 lbs 200 lbs
Daily calorie intake 2000 kcal 2000 kcal
Actual Calorie absorption 90% (2000 X .8) 1800 kcal 95% (2000 X.95) 1900 kcal
RMR 1200 1200
Natural NEAT 450 kcal per day 350 kcal
Thermic impact 5% (2000 x .05) 200 kcal 2.5% (2000 X 0.25) 100 kcal
Daily workout 250 kcal 250 kcal
Daily calorie balance
  • 300 kcal (weight loss)
0 kcal (weight maintenance)

* Results in this table are demonstrative values only and actual figures could be very different

Resting Metabolic Rate

The RMR and daily workout figures are identical to one another since a lower weight inevitably reduces RMR and calories burned during a workout. (note: the RMR could vary by up to 15%, but this is largely genetic and out of our control)

However, adaptive NEAT, thermogenesis and calorie absorption make the difference in outcomes rather different.

It is very likely that somebody who has lost weight will not be able to exist on the same amount of calories as somebody who weighs the same as them, but has retained this weight for a long period of time.

Add to this the 15% difference in RMR that can exist from person to person, and if you’re on the lower end of RMR, it really can feel like the world is against you when trying to lose weight.

However, please remember this: Everybody loses weight in a calorie deficit.

What is NOT happening:

  1. You are not eating less than 1200 kcals per day and still not losing weight (unless you weigh less than 100 lbs and even then you would need to be sedentary). Your body will retain a relatively stable RMR regardless of how much you diet. If you think you are eating 1200 kcals, exercising for an hour a day and still not losing weight you are probably vastly miscalculating the amount of food you are eating. (read underreporting)
  2. Your body is not seriously damaged by a lifetime of dieting. It has made some inevitable adaptations alongside some fixable adaptations that make losing weight more challenging. Losing weight can be hard, but we are here to support you.
  3. You are not defying the laws of thermodynamics. You can lose weight if you create an imbalance, everybody can. Calorie balance is not as simple as ‘calories in versus calories out’ (as illustrated above) but it is never, ever false.

What can be done?

Calorie flux

Avoid staying in permanent calorie deficits to minimise the impact of adaptive processes when losing weight.

Flux protects our metabolism from adaptive processes and allows us to build muscle, that is more metabolically active than fat.

Accept the facts

Your metabolic rate is your metabolic rate, it is not your fault and your body is not broken! Your metabolism may not be as you wish it to be, but only a small part of that is within our control. It is possible that another person with most of the same factors as you can lose weight at 2000 kcal and for you to lose weight you must consume 1500 kcal. This may not be fair, but if you want results it must be accepted. If you are not losing weight and you wish to, you are eating too many calories for weight loss. You may not think you are eating too many calories, but you are.

Note: If you are seriously concerned about your metabolic rate and are eating less than 1200 calories a day alongside regular exercise and not losing weight, this needs investigation beyond the scope of this book. Call your doctor immediately.

Consider food quality

Processed foods have a much higher absorption rate than non processed foods. They also have a lower thermic effect. The increased processes required to digest fibre, nutrient rich foods means we spend more energy digesting them AND absorb less of the calories in the process.

Reverse diet

Increasing calories while sustaining weight will slowly support increased NEAT, decreased absorption and increased thermic effect.

Monitor NEAT

Your body may not WANT to move as much when you are in a calorie deficit, but that doesn’t mean it CAN’T move as much. Track your steps, take the stairs, cycle to work and keep moving!

Conclusion (metabolism) 

When losing weight, our metabolism will always slow down, making the last few pounds much harder to lose than the first few pounds.

As we age our metabolism will slow down, making weight loss at 25 far easier than weight loss at 65.

Chronic dieting will cause adaptations to your metabolism, but:

1. They are not as extreme or damaging as you may think

  1. They are mostly fixable and/or avoidable with a sensible approach
  2. They will not be extreme enough to prevent all progress

Calorie balance is never false but it is simultaneously simple and complicated.

While energy in versus energy out is true – a variety of factors – from energy absorption to adaptive NEAT and the thermic effect of food to slowing RMR and even aging can make this law feel like a continuously moving object and our body an outlier to the laws of physics.

Provided you continue to view the facts objectively and adapt accordingly, you cannot fail to achieve the goals that matter to you.

Your body CAN reach its best version.

This is an excerpt from Transform for Life by Daniel and Alexandra Bartlett and available for all premium members.


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