Article 1: Obesity, weight-reducing programmes and constipation

The Authors

Elaine Anderson, Third-year Undergraduate Student in Nutrition

Jill Davies, Head of the Nutrition Research Centre both at South Bank University, London, UK.


Abstract
Obesity is caused by positive energy balance. This means that there is higher energy input from food than output through physical activity. Energy not used is stored as fat in adipose tissue around the body. There may be many reasons for weight gain and overeating can play an important role in positive energy balance. Other areas are genetics and socio-economic circumstances. Children born to two parents that are obese have an 80 percent chance of obesity later in life. If one parent is obese then the child has a 40 percent chance. Children or adolescents that are overweight have a stronger tendency to become obese adults. Some twin studies also support genetic theories (McIntyre, 1998). Factors such as low level of education, heavy alcohol consumption, chronic disease, low physical activity levels and, in women, bearing children were found to increase levels of obesity in people with low socio-economic status (McIntyre, 1998; Garrow, 1993).

Weight-reduction programmes
According to many sources weight reduction is the answer to reducing morbidity and decreasing mortality rate (Garrow, 1993; Pi-Sunyer, 1993; McIntyre, 1998). With a weight loss of 10kg, total mortality is reduced by more that 20 per cent. The rates of NIDDM and obesity-related cancer also decrease by 30 per cent and 40 per cent respectively. A weight loss of 5 to 10kg could assist in relieving problems such as back and joint pain, lung function and sleep apnoea (McIntyre, 1998). For an obese person to lose weight they would need either to reduce their energy intake from food, thereby inducing negative energy balance, or to increase their physical activity level or both. It is reported that during weight loss both fat and protein are lost: fat from adipose tissue (fat) and protein from lean tissue (fat-free mass) (Garrow, 1993). McLaren (1981) reports that the reduction due to energy intake over the first few days is a loss of fat-free mass rather than fat from adipose tissue. Garrow (1993) informs us that fat-free mass will be lost during a weight-reducing diet if the calorific value is found to be less than 1,000 kcal/day. A diet so low in calories would also restrict the intake of essential nutrients (Garrow, 1993). Diets available are many and varied such as those provided by primary health care teams and commercial weight-reducing clubs such as Weight Watchers, Slimming World, Slimming Club Magazine plus others.

Commercial weight-reducing diets provided by clubs such as Weight Watchers have changed over the years (McLaren, 1981). Since Weight Watchers began almost 30 years ago it claims to have helped nearly 25 million people (Hicks, 1997). In September 1996 a new diet regimen was launched that offers slimmers a daily points system that is dependent on gender, age, and weight at membership. This has put a stop to laboriously weighing foods and counting calories. Club members can now choose from a range of foods provided by Marks & Spencer and Boots. The diet places an emphasis on eating fruit and vegetables and reducing the intake of foods containing saturated fat (Hicks, 1997). Weight loss at Weight Watchers is aimed at 2-3lbs/week at first then reduces to 1.5-2lbs/week (Hicks, 1997). This amount of weight loss per week is also suggested by Garrow (1993) who has calculated that the reduction in energy intake would be between 500-1,000kcal (2-4MJ)/day and still provide essential nutrients.

Slimming World is another weight-reducing club established 30 years ago. In its booklet Personal Passport to Success it offers a weight loss programme, weekly classes, support and dietary advice. It also informs its club members of the need to eat more fruit, vegetables, reduce intakes of saturated fat and the need for high fibre foods. However, free will prevails and the day’s food choice is still the responsibility of the club member.

Foods not to be restricted are fruit, vegetables and whole grain cereals as these foods are necessary to provide the body with micronutrients and non-starch polysaccharides (NSP). A diet containing high amounts of NSP prevents constipation and bowel diseases (Department of Health, 1991; Garrow, 1993).

Constipation
 When energy intake is reduced NSP intake is also reduced (Garrow, 1993). Pi-Sunyer (1993) reports that one of the problems of weight loss is constipation and Cummings (1993) has stated that “complaints of constipation are common in people on low-fibre diets”.

Constipation is classified by “infrequent bowel habit of less than three times per week, transit time of five days or more and stool weight below 50g/day” (Department of Health, 1991). Presently in the UK 1 per cent of the population visit their general practitioner because of constipation, while up to 12 per cent feel they have symptoms of constipation and 10 per cent of the adult population actually suffer from constipation. This figure increases after the age of 60 years to above 20 per cent (Department of Health, 1991; Garrow, 1993). The Department of Health (1991) report that “median stool weight in the UK is about 100g/d, 95 per cent of the adult population passes between 30 and 260g/d, 46 per cent less than 100g/d and 18 per cent less than 50g/d”. It was also found that more women suffered from constipation and had lower stool weights in comparison with men.

The current intake of NSP in the UK is 13.9g/day (Ministry of Agriculture Fisheries and Food, 1995) which is marginally above the Dietary Reference Value of the individual minimum of 12g/day (individual maximum being 24 g/day) (Department of Health, 1991). Of these values 50 per cent of total NSP intake is provided by vegetables, whilst 40 per cent is provided by cereals (Department of Health, 1991). The role of NSP in the diet is to add bulk to faeces (Ministry of Agriculture Fisheries & Food, 1995). This occurs when dietary NSP remains intact after passing through the stomach and small intestine (Department of Health, 1991). However, it must be pointed out that not all NSP have the same effect on stool weight and bowel habit. Therefore bowel habit responses are highly variable when faced with soluble and insoluble NSP fractions (Department of Health, 1991). Since each NSP fraction has a different effect on bowel habit it is important that the diet contains a variety of foods that are able to provide both soluble and insoluble NSP “as a naturally integrated component” (Department of Health, 1991).

In order to ensure NSP intakes meet the DRV of 18g/day (Department of Health, 1991) people on weight-reducing programmes would be well advised where possible to opt for “high fibre” varieties of foods (Table I). However, caution will be needed in order to balance the energy intake against NSP intake.

People on weight-reducing programmes need to be aware of the need to balance energy intake against that of NSP in order to reduce the likelihood of developing constipation. Furthermore, individuals who are on such programmes for long periods may be increasing their risk of bowel-related disorders such as haemorrhoids, varicose veins, hiatus hernia and diverticular disease if attention is not given to NSP.

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