them to measure the energy released and then subtracting the energy lost as waste, he did not factor in the calories used to digest the food being eaten. It was a big mistake, because different foods need different amounts of energy to chemically break down before being absorbed in the gut.
Simply put, Atwater was wrong when he gave all dietary fibre the ballpark value of 2 kcal per gram, carbs and proteins 4 kcal per gram, and fat 9 kcal per gram. New findings show, for example, that we use up 25% more energy to digest carbs with high dietary fibre, taking the calories down from 2% to 1.5% per gram, reports the American Journal of Clinical Nutrition. Similarly, 20% of protein calories are used up in digestion, taking the calories you end up getting down from 4 kcal per gram to 3.2 kcal.
Food texture, too, has an effect on how much weight you gain. By the rule of the thumb, harder foods that are more difficult to chew provide fewer calories than softer variants of the same food, shows a study from the University of Japan. This is the reason why cooking adds to calories, as it changes the molecular structure of foods and makes it more easily digestible.
The most unexpected, however, is the new finding that links antibiotic overuse to weight gain. Yes, the same drugs that are aiding in the creation of deadly drug-resistant superbugs are also playing havoc with the 100 trillion good bacteria in our intestines that aid digestion and absorption of the food we eat, changing gut flora irreversibly.
Changes in the intestinal microbiome has already been linked to diseases such as asthma, autism, irritable bowel syndrome and Crohn’s disease.
Now a study from New York University shows that when mice bred in sterile environment were given gut bacteria from antibiotic-fed mice, they became 35% larger than mice with normal gut within five short weeks.
Findings from a study of 28,000 babies at Denmark’s Copenhagen University Hospital showed that those given antibiotics in the first six months of life were more likely to be overweight at the age of 7, even if they had a healthy birthweight and had mothers with a healthy weight. The study was reported in the International Journal of Obesity.
And it’s not just prescriptions that you have to be wary of. Healthy babies can acquire altered gut bacteria in their mother’s womb, or worse, in hospitals that have become permanent homes for lethal superbugs. And if they somehow escape microbial scarring at birth, there’s always the threat of antibiotics-laced meats that come from farm animals fed antibiotics to grow faster.
Since there’s no scientific evidence that repopulating our guts with healthy bacteria works, we have to watch what we eat. Antibiotics cannot be wished away, they are needed to fight lethal infections. What we need is monitored therapeutic use to escape superbugs and keep a check on expanding waistlines, which are precarious not just for our social life but also putting us at risk of potentially killer diabetes, heart disease and some cancers, like those of the breast, bowel and kidney.
Obesity kills 2.8 million people each year, says the World Health Organisation, and with 12% of the world’s population obese and growing, keeping track of things that make us fat suddenly makes more sense.