Why Am I Not Losing Weight in a Calorie Deficit?
If you are eating less but the scale is not moving, the energy gap may be smaller than it looks, normal changes in body water may be hiding a downward trend, or your body may have adjusted to earlier weight loss. A medication or a health condition such as an underactive thyroid can also play a part, and a GP can check for these.
This is general information, not medical advice. Weight loss varies between individuals, and the causes below are things to check with a health professional, not a diagnosis.
The 8 Causes at a Glance
Work down this checklist before cutting your food any further:
You are taking in more energy than you think.
Your energy needs are lower than your estimate.
Activity is doing less than you expect.
Day-to-day changes in body water are hiding the trend.
Your body has adjusted after earlier weight loss.
Sleep, stress or low mood are adding to what you eat.
A medication is affecting your weight.
A health condition or life stage is playing a part.
1. You Are Taking In More Energy Than You Think
Small amounts add up, and some of the biggest sources are easy to miss:
Drinks: soft drinks, sports drinks, flavoured milks and coffee with full cream milk and syrup all add energy, mostly from added sugars. Water has none.
Alcohol: alcohol has almost as much energy as fat, and one standard drink holds about 290 kJ. Drinking also lowers inhibitions, which can make less healthy food more tempting (Better Health Channel).
Portions: the bigger the serve, the more energy, which matters most for energy-dense foods and drinks high in fat or alcohol.
Snacks and extras: high-energy "junk" foods, which healthdirect describes as those over 600 kJ a serve, and eating when you are not hungry.
What to check: keep a food diary for a week, including every drink, and be honest rather than changing your habits while you record. Read the nutrition information panel on anything packaged.
2. Your Energy Needs Are Lower Than Your Estimate
Every calorie target starts from an estimate of how much energy your body uses, and those estimates are only approximate for any one person. Two people of the same age, sex and size with similar activity can need quite different amounts. Needs also change over time: people lose muscle as they get older, which slows the metabolism, and a smaller body uses less energy than a larger one.
What to check: make sure your target is your energy need at a healthy weight, from a calculator such as the Eat for Health daily energy requirements calculator with your ideal body weight entered, and compare it with your intake. A figure worked out at your current weight is about what keeps your weight steady, not a weight loss target. Our guide to working out your calories and macros for weight loss shows how the figures fit together. Keep the result at or above 5,000 kJ (1,200 calories) a day unless a health professional advises otherwise.
3. Activity Is Doing Less Than You Expect
Movement matters, but physical activity has little effect on weight unless it is combined with changes to eating, according to Australia's clinical guidelines. Those guidelines pair a reduced intake with about 300 minutes of moderate activity, or 150 minutes of vigorous activity, a week.
What to check: keep a physical activity diary for a week, noting each bout of 10 minutes or more. Compare your weekly minutes with the 300-minute figure, and look at what you eat on training days.
4. Day-to-Day Changes in Body Water Are Hiding the Trend
Scale weight moves up and down with body water, not only fat. Fluid retention can come with the premenstrual phase and with some medications, and swelling can be worse after sitting for long periods. Cutting back on salt can help reduce fluid retention. Weight lost in the first days of a very low carbohydrate diet is mostly water, not fat, and that water comes back when usual eating resumes. Even for people who manage their weight well, small fluctuations are common.
What to check: weigh yourself once a week and look at the trend from week to week, not a single reading. Measure your waist as well: the Better Health Channel suggests being guided by waist size rather than the number on the scales. See a doctor about any swelling in the legs or feet. To see progress as a share of your starting weight, use our guide on how to calculate your weight loss percentage.
5. Your Body Has Adjusted After Earlier Weight Loss
When you lose weight, the body responds. The NHMRC obesity guidelines describe an adaptation that slows weight loss: energy use drops, and levels of appetite-regulating hormones change in ways expected to increase hunger and reduce fullness after meals. These changes last for at least a year. In studies of lifestyle programs, weight loss tends to peak at around 6 to 12 months. Losing weight in a short time can also cost muscle, and muscle burns kilojoules while fat does not.
What to check: as your weight comes down, what your body uses each day comes down too, so the gap between that and your target narrows. Keep up muscle-strengthening activity on 2 or more days a week, and look for progress beyond the scale, such as your waist measurement. Slowing down is part of the body's normal response to weight loss. For what a realistic pace looks like, see how much weight you can realistically lose in a month.
6. Sleep, Stress or Low Mood Are Adding to What You Eat
Stress, low mood, poor-quality sleep and changing emotions can all lead people to take in more kilojoules than they need (healthdirect). Sleep helps control appetite and weight, and stress can change appetite.
What to check: aim for 7 to 9 hours of sleep a night with regular times, and notice whether you eat more when you are tired, stressed or upset. A GP, psychologist or counsellor can help with ongoing stress or low mood.
7. A Medication Is Affecting Your Weight
Some medications can cause considerable weight gain in a relatively short time, with some linked to weight gain at 12 weeks after starting. Examples in Australia's obesity guidelines include some medications for depression, bipolar disorder, epilepsy, migraine, diabetes and high blood pressure. The same guidelines note that combined contraceptives and hormone replacement therapy appear not to cause weight gain. Some medications also cause fluid retention. If you live with diabetes, see weight and type 2 diabetes.
What to check: list everything you take and when you started it. Talk to your doctor before making any change: a different medication or a change in dose can sometimes be considered.
8. A Health Condition or Life Stage Is Playing a Part
Some conditions make weight harder to shift:
Underactive thyroid (hypothyroidism): slows the metabolism. Signs can include tiredness, weight gain, bloating and feeling the cold, and many people live with it undiagnosed. See weight and thyroid conditions.
Polycystic ovary syndrome (PCOS): can cause weight gain or difficulty losing weight, along with irregular periods, acne and extra hair growth. See weight and PCOS.
Cushing's syndrome: a condition that can cause weight gain, especially around the torso, along with tiredness and mood changes.
Menopause: research suggests women gain roughly half a kilo a year between the ages of 45 and 55, and fat tends to move to the waist. Hormones are not thought to be the main cause; less activity, muscle loss with age, and symptoms such as low mood and tiredness all play a part (Jean Hailes). See weight changes after menopause.
Quitting smoking: people who quit for at least a year tend to gain more weight than those who keep smoking.
What to check: see a GP if any of these signs sound familiar. A GP can check for these conditions.
What to Check: A Summary
| Cause | What to check | Who can help |
|---|---|---|
| More energy than you think | Food diary for a week, drinks included | Dietitian |
| Needs lower than estimated | Target set at a healthy weight | Dietitian |
| Activity doing less | Activity diary; weekly minutes | Exercise physiologist |
| Body water | Weekly weigh-in, waist measure | GP if swelling |
| Body has adjusted | Smaller gap; strength training | Dietitian |
| Sleep, stress, mood | Sleep hours; eating when stressed | GP or psychologist |
| A medication | What you take and when it started | GP |
| A health condition | Signs such as tiredness or cold | GP |
When to See a Doctor
See a GP if you are struggling to lose weight with a healthy diet and physical activity, or if you notice any of these:
tiredness, feeling the cold or bloating along with weight gain
irregular or heavier periods, acne or extra hair growth
weight gain mostly around the torso
swelling in your legs or feet
weight gain after starting a new medication
low mood or stress that is affecting how you eat
A GP can check for medical causes, review your medications and refer you to a dietitian, exercise physiologist or psychologist. You can also see your doctor any time you are concerned about your weight or want help to lose weight.
When Lifestyle Changes Are Not Enough
If the causes above have been checked and weight is still hard to shift, a registered healthcare practitioner can talk through other treatments that may help, which can include medical weight loss treatment for some adults living with obesity. Any such treatment is used together with a healthy diet and physical activity, not instead of them. It has side effects, is not suitable for everyone, and outcomes vary between individuals. See whether diet and exercise alone are enough and what happens at a weight loss consultation.
Frequently Asked Questions
Is it possible to be in a calorie deficit and not lose weight?
Yes, for a while. Changes in body water can hide fat loss on the scale, and fluctuations are common. If the scale has not moved over several weeks, the deficit may be smaller than you think, your needs may be lower than estimated, or your body may have adjusted. A medication or health condition can also play a part.
Why am I not losing weight even though I am exercising and eating right?
Exercise alone has little effect on weight unless eating changes too, and a small gap is easy to close with drinks, larger portions or extra snacks. Keep a food and activity diary for a week to check. If both look right and nothing changes over several weeks, see a GP to rule out a medication or a condition such as an underactive thyroid.
Why am I not losing weight even though I'm running?
Running uses energy, but a kilometre of running uses about the same energy as a kilometre of walking; it just takes less time (Better Health Channel). Australia's obesity guidelines pair activity with eating less rather than relying on activity alone. Look at what you eat and drink on running days, and keep a food diary for a week, drinks included.
Why am I not losing weight on 1,500 calories a day?
1,500 calories is about 6,300 kJ. For a smaller or less active person, that may be close to what the body uses, so there is little or no gap. Energy needs vary widely between people. Compare it with your energy need at a healthy weight, record everything you eat and drink for a week, and talk to a dietitian before cutting further.
Why am I not losing belly fat even after exercise and diet?
Where the body stores fat can change with life stage. Around menopause, for example, fat storage tends to shift from the hips and thighs to the waist. Measure your waist too: it is a good guide to hidden fat around the organs. A waist of 94 cm or more for males, or 80 cm or more for females who are not pregnant, carries a higher health risk.
I used to be slim, but now I can't lose weight. What could be causing this?
Energy needs change with age. People lose muscle as they get older, which slows the metabolism. Many women put on weight around menopause, often because of reduced physical activity. Some medications and conditions can also play a part, so a GP check is worthwhile if your weight has changed without an obvious reason.
References
Eat for Health (NHMRC). Dietary energy, Nutrient Reference Values for Australia and New Zealand.
Eat for Health (NHMRC). Daily energy requirements calculator.
Better Health Channel (Victorian Government). Weight loss: common myths.
Better Health Channel (Victorian Government). Weight loss: a healthy approach.
Better Health Channel (Victorian Government). Walking for good health.
Better Health Channel (Victorian Government). Weight management services.
Jean Hailes for Women's Health. Weight gain at menopause: are hormones to blame?
This article is general information only and does not replace individual medical advice. Please speak with a registered Australian healthcare practitioner about your own circumstances.