1) Too much protein
Protein is vital for building muscle, but wolfing down a huge steak may not be the best route to getting stacked. ‘Most research shows that you can only digest about 30g of protein in one sitting,’ says fitness trainer David Marshall. ‘If you eat too much protein most of it will be stored as fat.’ Instead, eat a small amount every couple of hours, so your muscles have the fuel they need to grow stronger.

2) Not enough protein
Don’t go too far the other way, though. To pack on muscle, you need 1-2g of protein per kilogram of bodyweight each day. Although some of the best sources, such as red meat, are high in saturated fat, you should never skimp on protein. ‘It’s vital for muscle growth, and when combined with carbs it helps to keep your blood sugar levels stable so you don’t get energy spikes,’ says nutritionist Patrick Holford. Try low-fat sources such as cottage cheese and quinoa.

3) Cutting out fat
Fat may be high in calories but we need it for many reasons. ‘Fat-soluble vitamins, such as A and E, are found in healthy unsaturated fats from fish and olive oil,’ says nutritionist Carina Norris. ‘These good fats help lower cholesterol and keep arteries clear and are needed to synthesise hormones.’

4) Too much fruit juice
Orange juice may provide a decent dose of vitamin C, but it also packs huge amounts of calories in the form of fructose, a fruit sugar. ‘The fructose in juice can provide a great pre-workout energy boost,’ says nutritionist Thomas Midgley. ‘However, you should limit your intake at all other times because excess sugar will be stored as fat, as well as leading to dental problems.’

5) Not enough water
Thirsty? You’re already dehydrated. ‘We need water for every body function and if you don’t drink enough you won’t be able to perform at your best, physically or mentally,’ says Holford. ‘It’s best to drink little and often rather than sink a pint in one go.’

6) Too much saturated fat
Saturated fat – the kind found in animal products – attacks your body on a variety of fronts. ‘It raises your levels of LDL or “bad” cholesterol, which causes furred arteries and increases the risk of cardiovascular problems,’ says Norris. ‘It also increases the likelihood of developing certain cancers, including that of the prostate and small intestine.’ The British Heart Foundation recommends men eat no more than 30g of saturated fat per day.

7) Skipping breakfast
Fewer meals equals weight loss, right? Wrong. ‘Your metabolism slows down while you sleep, but upon waking you need food to kick-start your body,’ says Norris. ‘People who skip breakfast are more likely to succumb to unhealthy mid-morning snacks and less likely to lose weight.’

8) Not getting five a day
‘The nutrients and fibre contained in fruit and veg help protect us from many diseases such as heart disease and some cancers,’ says nutritionist Kellie Anderson of health organisation Maggie’s Centre. ‘They also help with long-lasting energy and weight control. No supplement can give the same benefits as eating the real thing.’

9) Eating late at night
‘We need our energy early in the day, not late at night when the body is preparing to slow down for sleep,’ says Anderson. ‘We also tend to make poorer food choices late at night like high-calorie pizzas or curries. Instead, eat five or six smaller meals throughout the day.’

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