Why is your weight not dropping despite diet and exercise?

You eat differently than you used to. You watch your meals. You move more. Training happens a few times a week. For the first few weeks your weight went down, and then it suddenly stopped.

Or an even more frustrating scenario: you feel you are doing everything according to plan, and the number on the scale barely changes.

Does that mean the diet is not working? Or that you simply need to eat even less?

Not necessarily.

Body weight is the result of far more processes than the amount of fat tissue alone. On top of that, the body gradually adapts to the new conditions during weight loss. That is why the rate of weight loss rarely stays the same from beginning to end.

Body weight is not only fat tissue

A bathroom scale does not measure how much fat you have. It measures the total mass of the body.

That includes fat tissue, muscle, water, glycogen, the contents of the digestive tract, and the mass of your organs and bones.

This is why a day-to-day change in the number on the scale very often tells us almost nothing about whether fat tissue was gained or lost on that particular day.

Body weight can be affected short-term by how much salt and carbohydrate you have eaten, by hydration, training, bowel movements or the menstrual cycle.

In a study published in 2023, women's body weight during menstruation was on average about 0.45 kg higher than in the first week of the cycle. The change resulted primarily from an increase in extracellular water, not from an increase in fat tissue.

That is why a single measurement can be misleading.

You get far more information by watching the trend over several weeks, ideally with measurements taken under similar conditions.

The energy deficit is not a fixed number

For the amount of fat tissue to decrease over the longer term, a negative energy balance is needed.

The problem is that energy requirements are not a number set once and for all.

Imagine someone who weighs 100 kg at the start. Their body needs a certain amount of energy both to maintain basic vital functions and to move the body during everyday activity.

After losing 10 or 15 kg, that requirement will already be lower.

A smaller body simply uses less energy.

Additional adaptive mechanisms may come on top of that. During weight loss, resting energy expenditure, spontaneous activity and total energy expenditure can all decrease. At the same time, hunger signals may intensify.

As a result, a deficit that started at, say, 500 kcal can be considerably smaller a few months later.

Research on the physiology of the weight-loss plateau shows that this gradual reduction in energy expenditure, together with increased appetite, is one of the main reasons the rate of weight loss slows over time.

Does metabolism really slow down?

Yes, but not necessarily in the way it is often portrayed on social media.

During weight loss, energy requirements fall primarily because body mass decreases.

So-called adaptive thermogenesis may also appear, meaning a drop in energy expenditure slightly larger than would follow from the change in body mass and composition alone.

A systematic review covering 33 studies and more than 2,500 people found evidence of such adaptation in many analyses. The authors did, however, point out very large variability between studies. In the best-designed work, the additional drop in energy expenditure was often small or not significant, and after a period of weight stabilisation the adaptation could partly disappear.

So this does not mean the body stops burning fat, or that you can "fail to lose weight because you eat too little".

It is far more accurate to say that during weight loss the body starts managing energy more frugally, and maintaining the previous deficit becomes harder.

You can move more in training and less through the rest of the day

One of the less obvious mechanisms concerns everyday, spontaneous activity.

Energy expenditure covers more than training. Walking, standing, gesturing, doing household chores or simply getting around during the day all matter a great deal.

This is NEAT, the energy expenditure that comes from activity not directly related to planned training.

If we are more tired during weight loss, we may unconsciously sit more often, walk less and cut down on spontaneous movement.

So you can complete 60 minutes of training and then move less than before for the rest of the day.

In practice, part of the energy spent during training is then "recovered" through reduced activity in other hours.

That is why assessing your activity should not stop at the question: how many times a week do I train?

The movement you do across the remaining fifteen-odd hours of the day matters too.

Physical activity does not always produce a big drop on the scale

Training remains one of the most important elements of looking after your health, but its effect should not be judged by kilograms alone.

A review covering 12 systematic reviews and 149 studies showed that training can reduce body weight, fat mass and visceral fat. The effect on body weight itself was, however, relatively moderate.

The situation with strength training is even more interesting.

A meta-analysis published in 2025 showed that adding resistance training to a reduced-calorie diet did not produce significantly greater total weight loss than diet alone. At the same time, people doing strength training lost more fat tissue and preserved fat-free mass better.

So it is possible for two people to lose a similar amount of weight while one of them ends up with a considerably more favourable change in body composition.

That is another reason to watch not only the kilograms, but also your waist circumference, how your clothes fit, your training progress and, if you have access to suitable methods, changes in body composition.

Sometimes we eat more than we think

This is one of the touchiest topics around weight loss, which is exactly why it needs explaining properly.

Underestimating how much energy you consume does not mean cheating or a lack of discipline.

It is simply very hard to judge the energy value of a diet by eye.

The easiest things to miss are the ones not treated as a separate meal: the oil used while cooking, sauces, peanut butter, additions to coffee, alcohol, drinks, small snacks or tasting food while preparing meals.

Bigger portions at the weekend, restaurant meals or a gradual increase in portion size can matter too.

Studies using the doubly labelled water method show that self-reported energy intake carries a considerable error. In a 2024 systematic review, most analyses covering people with class III obesity showed an underestimation of energy intake.

This does not mean you have to weigh every gram of food for the rest of your life.

But if your weight stays unchanged for a longer period, a few days of recording meals more precisely can help you check whether your diet really looks the way you think it does.

Activity can increase appetite

More movement means greater energy expenditure, but the body may partly respond to it by increasing hunger.

A 2021 meta-analysis indicates that training in people with overweight and obesity may lead to a small increase in fasting hunger. The average effect of exercise on total energy intake was small, though, and varied a great deal between individuals.

In practice, one person may notice no greater appetite after training, while another will automatically start increasing portions.

That is why the thought "I burned 500 kcal in training, so I can eat more" can very easily lead to overestimating actual energy expenditure.

Sleep matters too

Sleep is not a magic route to weight loss, and improving its quality alone will not replace an appropriate way of eating.

It can, however, make the whole process easier or harder.

In a study covering an 18-month weight-loss intervention, sleep parameters were analysed in the context of adherence to dietary recommendations, activity and weight loss. Better sleep was associated with a more favourable course of the process.

The latest systematic review, from 2026, also suggests that greater sleep satisfaction and better sleep efficiency may support weight loss. At the same time, the relationship between sleep duration alone and weight loss is not as clear-cut as it is sometimes presented online.

Short or poor-quality sleep can make meal planning harder, increase fatigue and reduce spontaneous activity. For some people it also comes with a stronger craving for high-energy foods.

What about stress and cortisol?

Saying that "cortisol blocks weight loss" is too much of a simplification.

Stress does not make the laws of energy balance stop working.

It can, however, affect the behaviours that matter for body weight: sleep, appetite, meal regularity, emotional eating, activity and recovery.

So chronic stress should not be ignored, but it is also not worth treating as the automatic explanation for every situation in which weight stops going down.

Could hormones be the cause?

Sometimes, yes, but hormonal disorders are not the most common explanation for a plateau.

One example is hypothyroidism. The Polish position statement on the diagnosis and treatment of obesity recommends assessing thyroid function in people with obesity. The basic screening test is TSH, and if the result is abnormal the diagnostic work-up is extended.

Cushing's syndrome can also lead to weight gain, but it occurs far more rarely, and routine cortisol testing in every person with obesity is not recommended. Diagnostics are carried out when characteristic clinical signs are present.

PCOS, sleep disorders, menopause or other conditions affecting appetite, activity and energy expenditure can matter as well.

If, despite well-run management, body weight does not change for a longer period, and particularly if additional symptoms appear, it is worth looking at the situation more broadly than through calories alone.

Check your medications too

Some medications can affect appetite, fluid retention, activity, or directly promote weight gain.

This applies among others to some glucocorticoids, antipsychotics, antidepressants, antiepileptics and certain drugs used in the treatment of diabetes.

This obviously does not mean the medication should be stopped.

If the change in body weight appeared after starting a new treatment, it is worth discussing with your doctor. In some cases it is possible to choose a therapy with a more neutral effect on body weight, but that decision should always be made on an individual basis.

Can eating too few calories stop weight loss?

This is one of the most popular myths.

The body does not switch into a mode where, with a real and sustained energy deficit, it stops using its energy stores entirely.

A very restrictive diet can, however, make weight loss considerably harder in indirect ways.

It can increase fatigue and hunger, limit spontaneous activity, worsen the quality of training and raise the risk of binge episodes or of abandoning the plan altogether.

That is why the answer to a plateau is not always to cut calories further.

A plateau is a normal part of weight loss

Slower weight loss is not proof of failure.

As body mass decreases, both energy expenditure and the body's response to weight loss change.

Modelling of weight-loss physiology shows that a plateau is a predictable consequence of the gradually shrinking difference between the energy taken in and the energy expended.

This is exactly why obesity treatment is increasingly seen as a long-term process that requires adjusting the strategy over time, rather than a few-week diet with one fixed calorie level.

Both the European Association for the Study of Obesity and the current AACE recommendations stress the need for individualised, long-term treatment and for judging results by more than BMI or the number of kilograms.

What to do when your weight has stopped dropping

Before you cut another few hundred calories from your diet, it is worth checking what is actually going on.

Look at the weight trend over several weeks rather than at the last two measurements. Take waist circumference and changes in body composition into account. Review portion sizes, additions to meals, drinks and the way you eat at the weekend. Check, too, whether you still move as much outside your training sessions as you used to.

It is worth assessing sleep, recovery, and whether the diet is one you can sustain without constant hunger.

If, despite genuinely following the plan for several more weeks, you see no change in the trend, the strategy can be adjusted. Sometimes that means a small change in energy intake, sometimes an increase in daily movement, and sometimes an entirely different look at the treatment so far.

In the case of obesity, it is also worth remembering that diet and activity are not the only available forms of therapy. In some patients, pharmacotherapy or other treatment methods matched to their health status and the stage of the disease are justified.

Summary

A lack of weight loss despite diet and activity does not always mean you are doing something wrong.

Sometimes fat loss is temporarily invisible because of changes in water. Sometimes energy requirements have fallen along with body mass. Sometimes the body has reduced spontaneous activity or increased hunger signals. Sleep, medications and certain conditions can matter too.

Effective weight loss should therefore not consist of endlessly reducing how much you eat.

When a plateau appears, it is worth treating it as information: time to reassess the situation and check what is currently limiting further progress.

And the number on the scale is only one element of that assessment.

Frequently asked questions

How long can a weight plateau last?

A few days, or even a few weeks, without a clear change in the number on the scale does not have to mean a true plateau. Short-term changes in hydration can effectively mask a small loss of fat tissue. That is why it is best to assess the trend over several weeks rather than single measurements.

If the scale is not moving, can I still be losing fat?

Yes. With strength training in particular, it is possible to lose fat tissue while better preserving or even increasing fat-free mass at the same time. In that situation waist circumference and body composition may change more than body weight itself.

Do I need to cut calories straight away?

No. First it is worth checking the weight trend, actual intake, daily activity, sleep and any changes in portion size. A further calorie restriction is not always the best solution.

Can metabolism be so slow that losing weight is impossible?

Energy expenditure can decrease during weight loss, and there are large metabolic differences between people. That does not mean fat loss is completely "blocked", though. Far more often the problem is that the initial deficit becomes smaller over time.

Can hypothyroidism make weight loss harder?

It can affect body weight and energy expenditure, which is why thyroid function is worth assessing in line with clinical indications. Hypothyroidism alone does not, however, explain most cases of long-standing obesity or a lack of weight loss.

Can training be working even though the scale is not changing?

Yes. Physical activity can reduce fat tissue, including visceral fat, and improve fitness, strength, insulin sensitivity and many other health parameters even when the drop in kilograms is small.

References

1. Nunes C.L. et al. Does adaptive thermogenesis occur after weight loss in adults? A systematic review. British Journal of Nutrition. 2022;127(3):451–469. doi: 10.1017/S0007114521001094.
2. Hall K.D. Physiology of the weight-loss plateau in response to diet restriction, GLP-1 receptor agonism, and bariatric surgery. Obesity. 2024;32(6):1163–1168. doi: 10.1002/oby.24027.
3. van Baak M.A., Mariman E.C.M. Obesity-induced and weight-loss-induced physiological factors affecting weight regain. Nature Reviews Endocrinology. 2023;19:655–670.
4. Bellicha A. et al. Effect of exercise training on weight loss, body composition changes, and weight maintenance in adults with overweight or obesity: An overview of 12 systematic reviews and 149 studies. Obesity Reviews. 2021;22(S4):e13256.
5. Beaulieu K. et al. Effect of exercise training interventions on energy intake and appetite control in adults with overweight or obesity: A systematic review and meta-analysis. Obesity Reviews. 2021;22(S4):e13251.
6. Lopez P. et al. Resistance training effectiveness on body composition and body weight outcomes in individuals with overweight and obesity across the lifespan: A systematic review and meta-analysis. Obesity Reviews. 2022;23:e13428.
7. Binmahfoz A. et al. Effect of resistance exercise on body composition, muscle strength and cardiometabolic health during dietary weight loss in people living with overweight or obesity: a systematic review and meta-analysis. BMJ Open Sport & Exercise Medicine. 2025;11(3):e002363.
8. Creasy S.A. et al. Effect of sleep on weight loss and adherence to diet and physical activity recommendations during an 18-month behavioral weight loss intervention. International Journal of Obesity. 2022;46:1510–1517.
9. Howes E.M. et al. Representation of adults with class III obesity in studies assessing validity of self-reported energy intake using doubly labeled water: A systematic review. Obesity Reviews. 2024;25(5):e13713.
10. Kanellakis S. et al. Changes in body weight and body composition during the menstrual cycle. American Journal of Human Biology. 2023;35:e23951.
11. Olszanecka-Glinianowicz M. et al. Obesity in Adults: Position Statement of Polish Association for the Study on Obesity, Polish Association of Endocrinology, Polish Association of Cardiodiabetology, Polish Psychiatric Association, Section of Metabolic and Bariatric Surgery of the Association of Polish Surgeons, and the College of Family Physicians in Poland. Nutrients. 2023;15(7):1641.
12. Busetto L. et al. A new framework for the diagnosis, staging and management of obesity in adults. Nature Medicine. 2024;30:2395–2399.
13. Nadolsky K. et al. American Association of Clinical Endocrinology Consensus Statement: Algorithm for the Evaluation and Treatment of Adults with Obesity/Adiposity-Based Chronic Disease, 2025 Update. Endocrine Practice. 2025;31(11):1351–1394.