I review my clients’ food diaries as part of my personal training service. Frequently, their food intake is spot on, but liquid calories are undoing their efforts. That glass of orange juice in the morning or wine at night is adding hundreds of extra calories to their weekly intake.

Research shows that when we consume solid food we naturally compensate by eating fewer calories throughout the day. However, when we consume liquid calories, we make no adjustment. In fact, we are likely to eat more. Fluid calories don’t suppress hunger or elicit compensatory dietary responses.

A study by Harvard University of 50,000 women found that those who increased their intake of sugar-sweetened beverages such as fizzy drinks or juice from one per week to one a day added 358 calories daily and gained significant weight.

Alcohol is the biggest calorie offender. At seven calories per gram it contains almost as many calories as pure fat (nine per gram) and has no nutritional value. Alcohol doesn’t just add empty calories, it also reduces the number of calories we burn from other sources.

Our bodies can store protein, carbohydrate and fat, but cannot store alcohol. Therefore, our bodies want to get rid of alcohol as quickly as possible. That means the processes of absorbing nutrients and burning fat are interrupted.

Now I’m not suggesting you become t-total. I wouldn’t wish a completely sober night in a cheesy club on anyone. However, you can regulate the number of calories you consume in a night out.

Cocktails are the most calorific. A long island iced tea contains a whopping 454 calories per 15 oz glass and an eye-popping 61 grams of sugar. No more than 25 grams of added sugar (six teaspoons) per day are recommended for women. An 8oz glass of pina colada contains 300 calories and 43 grams of sugar. Beer and cider aren’t much better, averaging at around 200 calories per pint.

You can save your waistline by sticking to spirits with a low calorie mixer or a light wine. Drink water or low calorie beverages between tipples and never exceed more than six units in one night (about four drinks).

So what about non-alcoholic beverages? The stats say these calories still add up. Skip that morning glass of orange juice and you’ll save 120 calories. Do you add sugar to milky tea or coffee? You’ll be consuming at least 50 calories per cup, more if you like two sugars. And as for those big mochas and hot chocolates with whipped cream that are served at our favourite coffee chains…keep walking if you don’t want to add up to 600 extra calories to your daily intake.

Fizzy drinks are also best avoided. A can of coke contains 142 calories, not to mention 39 grams of sugar (nine teaspoons) and other synthetic nasties. Fanta contains even more at 160 calories and 44 grams of sugar.

I try to drink at least two litres of water per day. This keeps me hydrated, boosts my immune system and improves my complexion, not to mention my waistline. In summer, I sometimes add squash, lime or lemon to water, while in winter I enjoy herbal or fruit teas. It means I can save those precious calories for nutritious meals that support my training, rather than waste calories on drinks which quickly undo my hard work.