Using child growth charts and centile lines, obesity is the term used when a child’s measured BMI is >98th centile and overweight is the term used when >91st centile. BMI or body mass index, is an individual calculation according to height and weight, but does not take account of individual body composition of fat or muscle; nor does it take account of bone – frame size or skeletal weight. It is none-the-less the accepted (but strictly speaking incorrect) medical reference for body fatness and is measured in primary schools in year 1 and 6 for national statistics. UK childhood obesity continues to rise, with a greater proportion of children from low income households being affected. In most instances this is due to the habitual energy intake from food/drink exceeding energy output from physical play and sports, referred to as positive energy balance. Body fat accumulates over time when this energy is not used up in physical activity, but (so as not to waste valuable food energy) is stored as fat for use in times of scarce food supply – food for humans was not always in such plentiful supply as it is today. There are various factors to consider – overall quantity and density of calories eaten, frequency and structure of meals, snacks and nutritious or sugary drinks. Obesity often runs in families with a combination of genetics, social and environmental factors. And so reversing positive energy balance and actioning food-related behaviour change is more desirable and do-able in childhood than it is in adulthood.
Reversing positive energy balance in childhood
A proportion of daily energy needs during childhood is required for growth – estimated at around 10-15%. Children have a greater capacity (and time available) for physical play and sports; developing this being helpful for longterm healthy weight maintenance. In itself, increasing physical activity is unlikely to yield weight loss, and so dietary measures are usually needed to reverse positive energy balance, towards an equilibrium, taking account of age-related growth spurts. Physical activity will yield improved muscle, which increases the metabolic rate responsible for overall energy needs. It can be a viscous cycle with overweight and obese children facing stigma at school, resulting in less participation in sports both in and outside school, which contributes to lower energy output. This impacts the energy balance and makes it more difficult to reverse positive energy balance. Young children who remain obese into teens risk increased mental health concerns and lower quality of life. Teenagers who start dieting may develop cycles of starving and binge-eating in efforts to control their weight, something which we see increasingly in young people. See my blog on 10 tips on maintaining a healthy weight.
Sugars are empty calories, fats contain essential nutrients
Low fat diets, as advised over the last generation, have seen fat energy replaced with sugar and processed carbohydrate energy. The food industry has created products consumers “want” such as low fat products, and higher sugar intakes are believed to be a more potent cause of obesity than fat. Sugars and fats both contain calories, which if regularly eaten is excess will certainly cause weight gain. Fats continue twice the calories per weight than sugars, but sugars are empty calories – in other words they have no other nutritional value. For our bodies to use sugar, valuable nutrients like zinc are needed to process it; the higher the sugar intake, the higher the loss of valuable nutrients from our body supply. Fats contains essential nutrients, necessary for brain, immune, hormone and nervous system function, without which we would become physically and mentally compromised. So, when thinking about getting the balance right, choose good fats – eg. fish, nuts & seeds, eggs, game, meat, oily vegetables eg, avocados, olives – eat dairy fats in moderation and ditch the empty calories from sugars and processed carbs wherever possible.