NOV – 15: COVER STORY
Not all calories are equal
Waiting for your friend at the coffee shop, you check the menu and spot your favourite chocolate brownie. You avoid sinning in the morning and almost zero in on a vegetable sandwich. But do you know a healthy sandwich contains 400 calories while a sinful brownie has 380! Calorie counts are more complicated than they seem. We help you understand why all calories are not equal.
Calorie count: Food labels around the world are based on a calorie count system developed in the late 19th century by American chemist Wilbur Olin Atwater. He calculated the energy content of various foods by burning small samples in controlled conditions and measuring them in terms of energy released as heat. He concluded that carbohydrates and proteins provide an average of 4 kcal per gm, while fats provide 9 kcal per gm.
Calorie absorption: Nutritionists are well aware that our bodies don’t burn food, they digest it and digestion takes different amounts of energy for different foods. According to Geoffery Livesey, a UK-based nutritionist, this can lower the number of calories your body extracts from a meal by anywhere between 5-25%, depending on the food eaten.
Brownie vs sandwich
In the brownie versus vegetable sandwich case, the label overestimates the calories derived from fibre and protein. The brownie is also softer in texture than the sandwich, a factor that is known to lower the energy cost of digestion. Refined sugar and flour in the brownie make calorie extraction easier than the wheat bread and vegetables in the sandwich containing complex carbohydrates.
How fibre makes a difference: We absorb more calories from refined foods because they lack fibre and bulk. High-calorie refined foods also slow down intestinal activity. They take up to five times longer to pass through the intestinal tract than do natural unrefined high-fibre foods (75 hours compared to 15) and the body absorbs calories during this entire time.
What cooking does: Cooking too can affect the number of calories the body gets from foods, suggests Richard Wrangham’s book Catching Fire: How Cooking Made Us Human. Cooking alters the structure at molecular level, making it easier for our body to break it up and extract nutrients.
Despite the large variations in the energy the body has at its disposal, none of it is reflected in the food labels, which at times may leave consumers in the dark about their dietary choices.
Why calories are important: Different food types contain different levels of energy and thus varying amounts of calories. For instance, 1 gm of carbohydrate has 4 calories as does 1 gm of protein while 1 gm of fat has more than twice, 9 calories.
When you donâ€™t use all the energy of the food you eat, it is eventually stored as fat. However, eating fewer calories than your body needs to function effectively is also damaging. The best way to lower your calorie intake is to substitute a lower calorie alternative for high-calorie food.
Dr. Liza Shah, well-known dietician and nutritionist says: â€œLearning how to read food labels properly enables you to make smarter nutrition choices. Ideally, a food label must provide relevant information on essential ingredients and nutrients, which is usually not the case. At times, labels are misleading. On some, sodium content is not mentioned. Sugar-free products are high in aspartame and are not fat-free.
Information on food labels should be read before purchase. At least, the approximate calories and nutrition values are known. The serving size is also important. Calories of food come from fats, proteins and carbohydrates. Labels mention number of calories in one serving that comes from fat. For instance, if there are 90 kcal in a serving, 30 calories, or one third, come from fat.