1. You're too stressed
Yes, being stressed can make it harder to lose weight – and not just because you're more likely to comfort-eat.
Chronic stress stimulates production of a protein – betatrophin – that reduces the body's ability to break down fat. Researchers at the University of Florida have found.
'Stress causes you to accumulate more fat, or at least slows down fat metabolism,' says the study's lead author Professor Li-Jun Yang. 'This is yet another reason why it's best to resolve stressful situations and to pursue a balanced life.'
Related: What stress does to your health and how to beat it
2. You're building muscle
...which isn't actually a problem, so relax. Muscle weighs more than fat, which means a new exercise regime may see your weight remain much the same even though your body shape is changing for the better.
That's why some super-toned sports stars are technically classed as obese even though they're at the top of their game.
Try measuring your waist or simply seeing how better your clothes fit rather than relying on the scales alone.
Related: Make sure you don’t lose muscle
3. You're skipping meals
Cut too many calories and your body will respond by slowing your metabolism to conserve energy.
The key is to eat three healthy, balanced meals each day to maintain energy levels and ensure you're not tempted to overeat later.
Skip breakfast, for example, and the brain is more likely to crave calorie-rich food later in the day, according to research at Imperial College London: in the study, people who'd missed their morning meal tended to eat around 20 per cent more calories at lunchtime.
Related: How to choose the best healthy breakfast
4. You're not calorie-smart
There are two key things to remember here.
First, all calories are not created equal: it's far more important to focus on the nutritional worth of food, rather than cutting calories alone. This point was hammered home in a report, published in the journal Open Heart, which highlighted how foods that contain the same calorie content can have very different effects on overall health.
Second, it's vital to curb your intake of 'empty calories' – those solid fats and added sugars that have little or no nutritional worth.
Top of the list of culprits? Alcohol. Drink a large glass of wine with your otherwise healthy meal at night, for instance, and you'll be consuming 228 calories – approximately the same found in an ice cream.
Related: Are you drinking more than you think?
5. You're not getting enough sleep
More waking hours means more time to eat, of course. And when you're tired, your ever-helpful metabolism slows to conserve energy, while your general sluggishness means you're more likely to crave sugary snacks.
Women who sleep for five hours or less each night are 32 per cent more likely to gain weight and 15 per cent more likely to be obese than those who get at least seven hours, according to a study from Case Western Reserve University.
Related: 10 reasons to get a better night’s sleep
6. You're not eating mindfully
Switched to a healthier diet? Good for you! But it's still important to exercise portion control.
UK food retailers are now selling food in bigger sizes and packages, meaning we're being tempted into eating a lot more than we did in the past.
Reducing portion sizes to 1950s standards would halve some of today's meals, according to a recent report in the British Medical Journal.
One solution, of course, is to avoid pre-packed food and cook everything from scratch. You can also trick yourself into eating less by using a smaller plate, chewing your food for longer, pausing between mouthfuls and avoiding distractions such as the TV while you dine.
Related: Can smaller plates aid weight loss?
7. You've been seduced by a fad diet
Hoping to lose a stone in a fortnight? It's time to get real. A healthy diet and exercise regime needs to be sustainable in the long-term.
If you're living on rice cakes and carrots and doing a tough daily workout, you'll probably lose weight – briefly. But try to keep that up for any length of time, and you'll find that your body – and mind – won't let you. After all, it's unrealistic, unhealthy and boring.
A safe rate of weight loss, according to the NHS Weight Loss Plan, is around 1lb to 2lb per week. So steer clear of fads and stick to making sensible lifestyle changes instead.
Related: Weird weight loss tips that might just work