They are often lithe, lean and toned — and frankly make us feel less than perfect — but are the fitness instructors who stalk our gyms as healthy as they look? A recent study in the Journal of Athletic Training reveals that gym professionals often fail to practise what they preach and that their rippling abdominals may be the result of an unexpected helping hand.

A survey of almost 300 gym instructors and aerobics teachers by the sports scientist Jessica Groth, of Western Michigan University, revealed that fewer than half — 41 per cent — did the recommended minimum of 30 minutes of moderate activity on five days a week, and 7 per cent said that they did none. Ms Groth suspects work pressure is to blame: “Gym instructors work long hours. Add families and personal lives and their time is spread very thinly.”

Groth also gave them a diet and lifestyle questionnaire that was even more revealing — they don’t follow the five-a-day rule. None ate enough fruit, vegetables, dairy foods, fish or carbohydrates to provide the vitamins and minerals needed to stay healthy. And they like a drink; 7 per cent of the women instructors admitted exceeding the US government alcohol limit every week (the UK maximum is 2-3 units a day).

So why do their bad habits not show? It may not be because they do more sit-ups than you do. Evidence suggests that people with perfect physiques are giving a false impression of what exercise can achieve. The secret of their flawless form, say experts, may be cosmetic surgery.

According to specialist cosmetic surgery chains — such as Transform, the largest in the UK — the number of otherwise slim and fit gym-rats requesting liposuction to remove, for example, saddlebags, has risen by a third in the past couple of years, as awareness of procedures has grown. Dr John Millard, a cosmetic surgeon and founder of the Advanced Body Sculpting Institute, who treats many high-profile clients, says that he sees “marathon runners who can’t get rid of their love handles”.

Dr Lorraine Ishak, the clinical director of Transform, says that this is the type of person for whom fat-reducing procedures were invented: “It’s a misnomer that liposuction is for fat people. If they regain weight, the fat distribution just shifts to another part of the body. Those who work out and eat sensibly are the best candidates.”

But we should not look to our “perfect” fitness instructors as physical role models, says the sports psychologist Dearbhla McCullough, of Roehampton University: “The body is not designed to be devoid of all fat. A fixation with removing tiny pockets of fat when you are slim and toned can spark into body-image disorders.”

Louise Sutton, the head of the Carnegie Centre for Sports Performance and Wellbeing at Leeds Metropolitan University, says that often the body-obsessed simply need to ease off: “If you over-exercise and under-eat, the body may increase stress hormones and store excess calories as fat in the abdominal region, giving you a pot belly. A lot of people find their stomachs are flatter when they don’t go hell for leather and starve themselves.”

Denise Page, at YMCAFit, the UK’s leading training organisation for gym instructors, says that fitness professionals having liposuction is “a worrying trend”. She says people of all shapes and sizes have fitness qualifications and many clients feel more comfortable with an instructor with natural curves and bulges: “You don’t need to be at peak physical fitness to help clients to achieve results. There’s no substitute for exercise to improve your health and looks.”

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