Embarking on a weight loss journey can be overwhelming with the multitude of diets and strategies that promise rapid transformations.

However, top nutritionists reveal that various factors can hinder progress on the scale, even when you’re putting in the effort.

Although diet is a significant component of weight management, elements such as sleep quality, stress levels, and meal timing also play crucial roles.

Anna Groom, a dietitian and spokesperson for the British Dietetic Association, shared with The Telegraph that while it might be tempting to opt for ‘quick-fix diets’ to shed post-holiday pounds, these methods often result in short-term benefits and can perpetuate harmful dieting cycles.

“Though they may offer immediate results, these diets are typically too restrictive to maintain, causing additional stress and disappointment,” she explains.

“Achieving sustainable weight loss requires a comprehensive approach that includes evaluating your mindset, physical activity, and overall lifestyle choices.”

With this in mind, these are the 12 most common mistakes people make when dieting – and how to fix them.

1. Eating too little 

One of the top dieting mistakes people make is eating too little, according to Dr Abby Hyams, chief medical officer at Medicspot.    

According to the NHS, an average man needs to eat around 2,500 calories a day and an average woman needs 2,000 calories a day to maintain their weight. However, this varies based on factors such as height and weight.

To lose weight, you need to consume fewer calories than you burn, which is known as creating a calorie deficit. This can also be achieved by increased physical activity. 

However, significantly cutting down the amount of calories you eat in a day can be harmful to your progress.

When the calories you consume are too low, your body fights back. 

‘The brain slows metabolism to conserve energy and ramps up your appetite,’ Dr Abby Hyams told The Telegraph. ‘It’s the body’s way of protecting you from perceived starvation.’

Dr Hyams recommends aiming to eat just 300-500 calories below your maintenance level to lose weight.

‘You’ll lose weight more slowly but keep it off – and have energy to live your life and exercise,’ she says. 

2. Not eating enough protein

Protein, which is found naturally in meat, fish, eggs and dairy, has become a dieting buzzword in recent years.

And according to the experts, there is good reason for this.

Protein increases satiety (the feeling of fullness) and can even boost metabolism. 

But many people overlook the impact of prioritising protein in their meals, eating low-calorie meals which aren’t filling. 

‘People often cut calories without thinking about where they come from,’ says Dr Hyams. 

‘They’ll have a salad with no protein, then wonder why they’re starving by 3pm.’ 

Protein is digested slowly, triggering satiety hormones like GLP-1 and reducing the hunger hormone, ghrelin. 

Dr Hyams recommends aiming for 20 to 30g of protein per meal, such as a palm-sized portion of chicken, fish, eggs or tofu, 150g of Greek yogurt or 100g of cottage cheese. 

3. Not eating enough fibre 

Gut scientist Dr Emily Leeming recommends bulking out meals with fibre to avoid feeling hungry between mealtimes. 

Fibre is a crucial component of a healthy diet, offering extensive benefits including improved digestive health, better blood sugar control, lower cholesterol levels and enhanced weight management by promoting fullness. 

A high-fibre diet is strongly associated with a reduced risk of heart disease, type 2 diabetes, stroke, and certain cancers. 

Dr Leeming recommends swapping white bread, pasta and rice for wholegrain varieties. 

4. Grazing on ‘free foods’

While it can be easy to forget about the biscuits you ate while you made a cup of tea, the chips you finished from your partner’s plate or the splash of olive oil over your salad, these calories can quickly add up

We underestimate our intake by about 30 per cent, according to the National Diet and Nutrition Survey. 

As a solution, experts recommend tracking food intake and being aware of mindless eating. 

5. Drinking your calories

The hidden calories in fizzy drinks, fruit juice and milky coffees have long haunted dieters.  

A recent Daily Mail article revealed that coffees from high street cafes can have an alarming number of calories.

For example, a trendy Black Sheep Coffee iced turmeric matcha latte with semi-skimmed milk has 279kcal.

Luxury hot chocolates can have as many as 500 calories – the same as a nine rashers of bacon.

Even milky teas or a nightly glass of wine can add hundreds of calories a week.

The good news is that it’s easy to swap large drinks for smaller ones, skip syrups and opt for sugar-free options.

6. Hitting the treadmill but not the weights

While cardio is great for getting in shape, consistent, moderate-volume training, including exercises like squats and deadlifts, causes muscles to grow, strengthening them while improving body composition and metabolic health.

A meta-analysis in Obesity Reviews found resistance training, plus a calorie-controlled diet, was the most effective fat-loss strategy.

‘Building muscle is your secret weapon for long-term weight management,’ says Dr Hyams. 

7. Weekday dieting – and weekend binging 

Dieting religiously throughout the week but falling off the bandwagon at the weekend is a common problem that could send your diet backwards. 

A solution to this is planning treats and higher-calorie meals into your calorie goals rather than taking an ‘all or nothing’ approach.

8. Eating at the wrong times 

Intermittent fasting, such as fasting for 12 hours then eating for 12 hours, can be a useful tool for burning fat

But many people focus on fasting in the morning, which can mean overindulging in the evening, according to experts. 

Skipping breakfast can mean missing essential nutrients like calcium and iron, leading to lower energy levels, ‘brain fog,’ and increased cravings for high-calorie foods later. 

It is linked to poorer cardiovascular health, increased risk of type 2 diabetes, higher blood pressure, and potential weight gain.

A study in Jama Internal Medicine found that early time-restricted eating between 7am and 3pm led to 50 per cent more weight loss than eating across 12 hours or more.

9. Eating big portions

It can be easy to overestimate how big a portion should be, particularly with items such as cereal, past and rice. 

The solution is to weigh out measure portions until you have trained your eye to see what the right amount is. 

10. Not getting enough sleep

Lack of sleep, particularly less than six hours per night, directly causes weight gain by disrupting hunger hormones (increasing ghrelin, decreasing leptin), raising cortisol and increasing cravings for high-calorie, sugary foods. 

Fatigue reduces physical activity, further promoting weight gain, while poor sleep also lowers glucose tolerance. 

A study in The Annals of Internal Medicine found just two nights of limited sleep increased hunger and cravings – particularly for high-carb, calorie-dense snacks. 

The solution is to get more shut-eye by going to bed earlier and reducing screentime in the evening.

11. Not feeding your gut

The gut is home to trillions of microbes – mainly bacteria, but also viruses and fungi – known as the gut microbiome.

These microbes help break down food, support the gut lining and produce compounds that influence digestion, inflammation, metabolism and immune function.

When the microbiome is in balance, beneficial bacteria help keep the gut stable and suppress more harmful strains.

But when that balance shifts – a state sometimes called dysbiosis – it can lead to symptoms such as bloating and irregular bowel habits, and has been linked in research to conditions including weight gain, type 2 diabetes and heart disease.

To keep your gut happy, prioritise fruits and vegetables, pulses and wholegrains and fermented foods, like live yoghurt or sauerkraut. 

12. Relying on willpower

‘One of the biggest diet mistakes is believing willpower is enough,’ Sandra Roycroft-Davis, founder of Slimpod and author of The Weight’s Over – Take Back Control, told The Telegraph. 

‘In fact, up to 90 per cent of our eating is driven by the subconscious. That’s why we often ‘know what to do but can’t do it’.

‘Willpower is like a battery – it runs out,’ she explains. ‘It’s not that you lack discipline; your brain is doing what it thinks you need. Diets fight your brain. Instead, you need to retrain it.’

The solution is to reflect on your habits and work out what your triggers are. 

‘Once aware, you can disrupt the pattern,’ said Ms Roycroft-Davis.

‘If you slip up, reframe it – say “this is just a wobble”, not “I’ve failed.” It breaks the guilt cycle.’