All this week鈥檚 questions and answers come from the Last Word website. These give only a taste of the answers and conversations that take place online. If you enjoy this weekly magazine column but would like more, or if you want an answer to a question quickly, visit 鈥� Ed
Are all calories (from all food types) equal in terms of causing weight gain? That is, if I eat complex carbohydrates to the value of 1000 calories, are these as likely to increase my body fat as eating fat or sugar to the value of 1000 calories?
鈥� Yes and no. The calories are the same. Once your body has converted the consumable compounds to a common compound (acetate, say) then there is no difference between the foods that were converted, whether protein, fat or carbohydrate.
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However, not all food compounds are equally well converted, absorbed and assimilated. Many starches are poorly digestible, such as polysaccharides. A great deal of unrefined foods pass right through your gut in sheaths of collagen, cellulose and similar poorly digestible natural plastics. Even animals that can digest these with the help of microbes usually need to digest the food twice, either by regurgitating the food after the first pass into the stomach, or by eating it again once it has been excreted. Ask any rabbit or termite about coprophagy.
Jon Richfield, Somerset West, South Africa
鈥� If you restrict the number of calories in your diet, you will not show any difference in weight loss whether you restrict calories from fat or calories from carbohydrates. This has been studied fairly extensively. An example study is 鈥溾�� (The New England Journal of Medicine, vol 360, p 859). The researchers found there was no significant difference in weight loss or in waist circumference for people eating diets that contained differing proportions of carbohydrates, fat and protein.
However, this does not mean you will experience the same success in a diet which restricts fat as in one that restricts carbohydrates. We react differently to different foods, and fats help us feel satiated. In this study, subjects only ate what the researchers gave them, but you will not have this type of enforcement.
A balanced, calorie-restricted diet is the best way to diet. Too little fat and you will often feel hungry; too little carbohydrate and you will feel tired and weak. Also, keep in mind that high-fat, high-protein diets place you at a greater risk of heart disease.
Araneae, No address supplied
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