Читать книгу Why Men Don’t Iron: The New Reality of Gender Differences - Anne Moir - Страница 9

The normal woman cannot lose weight by exercise alone but must also go on a diet; this factor probably makes women much more sensitive than men about their food intake. Men can lose weight by increasing their physical activity even if what they eat remains the same. Research at the Lenox Hill Hospital, New York, found that: ‘Unfortunately, while there is good evidence for such an effect in men, there is little if any evidence for a similar effect in women. Weight loss with exercise does not readily occur in women unless accompanied by caloric restriction.’⁷

At the University of Limburg at Maastricht in Holland, 16 men and 16 women were put through a five-month endurance training programme and their average daily metabolic rate – the amount of energy they each needed to keep their body functioning – was measured. All 32 of the subjects increased their physical activity by 60%, but the effects on the sexes were quite different. The men’s metabolic rate increased markedly: at the end of the 20 weeks they needed an extra 800 calories of food a day just to maintain their body weight, but no such change was detected in the women. The increased rate of exercise was burning the calories off men, but not off women, whose metabolic rate scarcely changed.⁸ Life is not fair. A man can jog away the pounds, but a woman cannot. She has to diet too.

It has long been known that men have less fat and more muscle than women. The average male body is one-seventh fat (15%), while fat makes up more than a quarter of the average woman’s body (27%). Weight for weight, she has 80% more body fat than he does. If she tries to get her body fat below 12%, by diet or extreme pysical excercise, normal body functions are impaired. For the male, that lower limit for fat is 3%.⁹

Equally striking is the sexual difference in musculature. In men 40% of body weight consists of muscle. Women have only about half this amount (23%). In the adolescent female the fat to muscle ratio increases as she adds fat to the pelvic area and breasts (her breasts contributing only four per cent of that total). In puberty the male growth spurt is accompanied by a hormonally stimulated jump in muscular development which typically doubles his physical strength.

Normal exercise increases the male’s metabolic rate. He then needs more energy from food to maintain a constant weight. The Lenox Hill Hospital study found that the female metabolic rate is little affected by exercise, so her exercise regime will not require more food. Nearly every man jack can lose weight by following the Jane Fonda Workout, but Jane can’t. A possible reason for the personal effectiveness of her own regime is found in Ms Fonda’s admission that her weight-reducing efforts had ‘been accompanied by bouts of bulimia’.¹⁰

A survey by Cosmopolitan magazine found that a quarter of its readers were perpetually on a diet, and that one-third of those dieters vomited to make themselves lose weight.¹¹ That incidence of bulimia nervosa seems high; in the general population the figure is about one young woman in 33, while the occurrence of this disorder in males is a mere one-tenth of that in females.¹²

Women are fond of reminding us that food can spend ‘a moment on the lips and a lifetime on the hips’. For them that is true, but for men it is not. They are different.