Why Am I Not Losing Weight? 8 Reasons From a Dietitian
"Why am I not losing weight?" is one of the questions I hear most often in clinic.
You've cut back, you're walking more, maybe you're even counting calories, and the scales still won't budge. It's frustrating, and it's easy to start wondering whether your body is "broken" or whether you simply don't have enough willpower.
Usually, neither is true.
As a Registered Dietitian specialising in weight management, with over 10 years' experience in the NHS and private practice, I've found there's usually an explanation for a weight loss plateau, and often there are practical things we can change. I've struggled with my own weight in the past too, so I know how disheartening a stuck scale can feel.
Here are eight of the most common reasons I see, what the evidence tells us and what you can do about them.
Why am I not losing weight in a calorie deficit?
If your weight hasn't changed for several weeks, one possibility is that your calorie deficit is smaller than it seems. Another is that your body now needs less energy than it did when you started losing weight.
Neither means you've failed. They're simply useful clues about what might be happening.
8 reasons you're not losing weight
1. Your calorie intake may be higher than you realise
This isn't about honesty or willpower. Keeping track of everything we eat and drink is genuinely difficult.
Research comparing self-reported food intake with objective measures shows that people commonly underestimate how much energy they consume (Ravelli and Schoeller, 2020).
And it's rarely one obvious thing. A splash of oil when cooking, a few of the kids' leftovers, a milky coffee, handfuls of snacks or a "small" glass of wine can all add up without us really noticing.
Try this: for one ordinary week, jot down everything you eat and drink, including tastes, nibbles and drinks. Don't judge it or try to have a "perfect" week. You're simply looking for patterns.
2. Your weekends look very different than your weekdays
In a European study of more than 1,400 adults taking part in a weight loss maintenance programme, weight typically increased over the weekend and came down again during the week (Turicchi et al., 2020).
A small weekly rhythm like this is completely normal. But if you're very restrictive Monday to Thursday and then eating and drinking significantly more from Friday night onwards, the weekend can reduce or cancel out the calorie deficit you've created during the week.
Try this: you don't need a "perfect" weekend. Instead, try to avoid the restrict-all-week, overeat-all-weekend cycle. Enjoy the meals and foods that matter to you, while keeping the rest of your weekend reasonably similar to your normal routine.
3. Your drinks are adding up
Calories in drinks are particularly easy to overlook.
Alcohol contains 7 calories per gram, almost as many as fat. The NHS says a standard glass of wine can contain up to 158 calories, while some pints of stronger lager can contain up to 222 calories (NHS, 2023).
It's not just alcohol. Milky coffees, juices, smoothies and sugary fizzy drinks can contribute more energy than you realise too.
Try this: choose your drinks on purpose rather than automatically. You might alternate alcoholic drinks with water, choose smaller glasses, switch some drinks for lower-calorie alternatives or have some alcohol-free days each week.
4. You're judging progress by one weigh-in
Body weight naturally fluctuates from one day to the next because of factors including hydration, food in your digestive system and normal changes in body water.
Research has also identified weekly patterns in body weight, so a single number on the scales tells you surprisingly little about whether you're actually losing body fat (Turicchi et al., 2020).
Regular self-weighing as part of a wider weight management approach has been associated with greater weight loss, although weighing by itself doesn't appear to make much difference. In one review, weekly and daily weighing produced similar results (Madigan et al., 2015).
Try this: if weighing helps you, weigh under similar conditions and focus on the overall trend rather than one reading. Look at what is happening over several weeks.
And if weighing negatively affects your mood or relationship with food, it doesn't have to be your main measure of progress. How your clothes fit, your energy levels, fitness and other health markers can matter too.
5. You've reached a weight loss plateau
Weight loss plateaus are normal. They don't mean your metabolism has "stopped working".
As you lose weight, your body becomes smaller and generally needs less energy. That means the amount of food that created a calorie deficit at the beginning of your weight loss journey may eventually become closer to the amount you need to maintain your new weight.
Your body may also adapt slightly to weight loss by using less energy than we would predict from the change in body size alone. This is known as adaptive thermogenesis. Research suggests the effect is real, but its size varies considerably and tends to be smaller in higher-quality studies (Nunes et al., 2022).
In other words, your metabolism hasn't suddenly switched off.
Try this: rather than immediately cutting your food intake further, go back to the basics. Look at portion sizes, drinks, weekends, snacking and how much you're moving throughout the day.
And remember: if you've lost weight and are now maintaining it, that is progress too.
6. You're short on sleep
Sleep and appetite are closely linked.
A systematic review found that when people were partially sleep deprived, they consumed around 385 more calories per day on average across the studies included, without a corresponding increase in energy expenditure (Al Khatib et al., 2017).
The studies were relatively small, so that doesn't mean everyone automatically eats an extra 385 calories after a bad night's sleep. But the overall pattern will probably feel familiar to anyone who has found themselves reaching for quick, energy-dense foods after a terrible night.
Try this: think of sleep as part of your weight management plan rather than something completely separate. A reasonably consistent bedtime and a wind-down routine can help.
And if broken nights are outside your control right now, give yourself some flexibility. Progress may simply be slower during this stage of life.
7. You're expecting weight loss to happen faster
Slow weight loss is still weight loss.
The NHS suggests around 0.5 to 1kg (1 to 2lb) per week as a general guide for people trying to lose weight, but this isn't a target everybody needs to hit (NHS, 2026a).
Some weeks you may lose more, some weeks less and sometimes the scales won't change at all. Smaller losses can still add up to meaningful progress over time.
The problem is that people often interpret a week without a loss as evidence that "it's not working" and give up before the longer-term trend has had a chance to appear.
Try this: judge progress over several weeks rather than several days. And give yourself credit for the habits you're building, not just the number on the scales.
8. A medicine or health condition is playing a part
Sometimes there are other factors affecting weight.
The NHS lists some medicines, including certain steroids, antidepressants and beta blockers, among those that can contribute to weight gain. Health conditions including an underactive thyroid and Cushing's syndrome can also affect weight.
Hormonal changes around perimenopause and menopause can make weight management more challenging for some women.
Weight gain or difficulty losing weight is also one of the main symptoms of polyendocrine metabolic ovarian syndrome (PMOS, previously called polycystic ovary syndrome or PCOS) (NHS, 2026b).
Try this: never stop taking prescribed medication without speaking to your GP or pharmacist. If you've experienced unexplained weight changes or think a medicine or health condition could be contributing, speak to a healthcare professional.
You can also read my guides to [diet and PCOS/PMOS] and [diet and the menopause].
What should I do if I'm still not losing weight?
If you've worked through this list and still feel stuck, it doesn't mean you're doing everything wrong.
Often there isn't one dramatic problem. It's a combination of several small things which, together, are enough to stop your weight moving in the direction you'd like.
In my experience, simply cutting back harder often isn't the best solution. It can leave you hungry, frustrated and more likely to end up back in the yo-yo dieting cycle I've written about before.
What helped me personally was learning to eat more intuitively and listen to my hunger and fullness again rather than starting another strict diet.
Support and accountability can also help. In the self-weighing review mentioned above, interventions that included additional accountability, such as regular check-ins, were associated with greater weight loss (Madigan et al., 2015).
Not sure what's holding you back?
That's exactly why I created my free guide, Why Can't I Keep the Weight Off? The 5-Minute Weight Loss Audit. It takes five minutes and helps you spot the everyday habits that might be keeping you stuck, so you know where to focus first.
If you'd like support that fits your life, find out how I help with weight loss or book a free discovery call.
No detoxes. No fad diets. No shame.
Frequently asked questions
Why am I not losing weight even though I'm eating less?
There are several possible reasons. Your calorie deficit may be smaller than it seems because of portions, drinks, snacks or differences between weekdays and weekends. Your energy requirements may also have decreased if you've already lost weight (Ravelli and Schoeller, 2020; Nunes et al., 2022).
Before making another big change, look at your weight trend over several weeks rather than a few days.
Can eating too little stop you losing weight?
Eating too little doesn't make the laws of energy balance stop working, although your body can adapt to weight loss and energy restriction by reducing energy expenditure to some extent (Nunes et al., 2022).
Continually cutting calories lower is not necessarily the answer to a plateau.
Very-low-energy diets of under 800 calories per day should only be considered in specific circumstances as part of a specialist weight management service, with appropriate clinical support and supervision (NICE, 2025).
How often should I weigh myself?
There's no single right answer.
One systematic review found that weekly and daily weighing produced similar results (Madigan et al., 2015). Choose an approach that gives you useful information without negatively affecting your mood or relationship with food.
The overall trend matters much more than an individual number..
How much weight should I lose a week?
The NHS suggests around 0.5 to 1kg (1 to 2lb) per week as a general guide, but you don't have to lose this amount every week for your progress to count (NHS, 2026a).
Weight loss is rarely perfectly linear. Smaller losses over time can still be meaningful and sustainable.
Should I see my GP if I can't lose weight?
Consider speaking to your GP if you've gained weight without an obvious explanation, have other new symptoms, or think a medicine or underlying health condition may be contributing to your weight.
This article gives general information and does not replace individual advice from your GP or a Registered Dietitian.
Caroline Bletcher is an HCPC Registered Dietitian (DT29447) specialising in weight management, with over 10 years' experience in the NHS and private practice.
Al Khatib, H., Harding, S., Darzi, J. et al. (2017) 'The effects of partial sleep deprivation on energy balance: a systematic review and meta-analysis', European Journal of Clinical Nutrition, 71, pp. 614–624. doi: 10.1038/ejcn.2016.201.
Madigan, C.D., Daley, A.J., Lewis, A.L., Aveyard, P. and Jolly, K. (2015) 'Is self-weighing an effective tool for weight loss: a systematic literature review and meta-analysis', International Journal of Behavioral Nutrition and Physical Activity, 12, 104. doi: 10.1186/s12966-015-0267-4.
NHS (2023) Calories in alcohol. Available at: https://www.nhs.uk/live-well/alcohol-advice/calories-in-alcohol/ (Accessed: 20 October 2026).
NHS (2026a) Overweight and obesity in adults. Available at: https://www.nhs.uk/conditions/overweight-and-obesity/ (Accessed: 20 October 2026).
NHS (2026b) Polyendocrine metabolic ovarian syndrome (PMOS). Available at: https://www.nhs.uk/conditions/polyendocrine-metabolic-ovarian-syndrome-pmos/ (Accessed: 20 October 2026).
Nunes, C.L., Casanova, N., Francisco, R., Bosy-Westphal, A., Hopkins, M., Sardinha, L.B. and Silva, A.M. (2022) 'Does adaptive thermogenesis occur after weight loss in adults? A systematic review', British Journal of Nutrition, 127(3), pp. 451–469. doi: 10.1017/S0007114521001094.
Ravelli, M.N. and Schoeller, D.A. (2020) 'Traditional self-reported dietary instruments are prone to inaccuracies and new approaches are needed', Frontiers in Nutrition, 7, 90. doi: 10.3389/fnut.2020.00090.
Turicchi, J., O'Driscoll, R., Horgan, G., Duarte, C., Palmeira, A.L., Larsen, S.C., Heitmann, B.L. and Stubbs, J. (2020) 'Weekly, seasonal and holiday body weight fluctuation patterns among individuals engaged in a European multi-centre behavioural weight loss maintenance intervention', PLoS ONE, 15(4), e0232152. doi: 10.1371/journal.pone.0232152.
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