Evidence is accumulating that the traditional advice to prevent obesity is ineffective. Weight gain is seen my the mainstream establishment as simply the result of a positive energy balance caused by either too little energy expenditure (exercise) or too large an energy intake (food). However, recent research is starting to implicate metabolic dysfunction as being very much involved in the aetiology of obesity, and its related conditions such as diabetes and cardiovascular disease. Rather than the energy intake directly being responsible for weight gain, instead it is the type of foods eaten that are responsible for the development of the underlying metabolic syndrome that then results in weight gain. To support this contention, studies consistently report that exercise is less effective that dietary improvements in long term weight loss programmes involving obese individuals
For example, researchers1 have analysed data from the Oslo Diet and Exercise Study to investigate the effect of favourable changes in diet in relation to reductions in body size and improved metabolic status. Subjects comprised of 187 men (≈50% of which had metabolic syndrome) with a mean age of 45, who were assigned to a diet protocol, an exercise protocol, a diet plus exercise protocol or a control protocol. A diet score was created in order to classify the quality of subject’s diets. The dietary intervention included counselling as well as recommendations to spread energy intake throughout the day, to increase consumption of fish, vegetables and fibre rich foods as well as to reduce intakes of sugar, saturated fat and salt (if subject had high blood pressure). Exercise involved jogging or fast walking three times a week (total 1.8 hours per week).
Baseline characteristics were similar amongst the groups. After 1 year, energy intake had fallen in the diet and diet plus exercise groups, but not the exercise or control groups. The change in energy intake was positively associated with changes in body weight, waist circumference, plasma leptin and systolic blood pressure. In addition, the diet score in the diet group increased (meaning improvements), whereas it decreased an equivalent amount in the exercise and control groups. Weight loss was 5-7kg in the diet group compared to 2kg in the exercise group, which equated to a 3.5kg change in weight based on 10 point improvement in diet score. Decreases in waist circumference were 5-7cm in the diet group but only 3cm in the exercise only group. Blood pressure decreased by 5-6mm Hg in the diet group, by 2mmHg in the exercise only group.
This study confirms that improvements in diet can result in significant alterations to metabolic parameters and physical characteristics. improvements in diet showed beneficial effects on weight, waist circumference, body fat, systolic blood pressure, plasma concentrations of total and LDL cholesterol, fasting glucose, fasting and pre-load insulin and leptin. These results were independent of the group the subjects were in and independent of energy intake. Changes in energy intake showed very small associations with biochemical parameters when compared to changes in dietary quality. In addition, there were only small changes in the exercise and control groups, but large changes in those who made improvements to the their diets. These results add weight to the importance of diet quality over exercise and restricted energy intake when it comes to favourable weight changes and improvements in metabolic function.
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