I don’t know for how long parents have been advised not to feed their kids too much fat. ‘Eating fat makes them fat’ is the usual message here, and therefore eating less of this particular foodstuff is the way to put a break on the burgeoning rates of overweight and obesity we’re seeing in our children. This week, in a seeming ‘about-turn’ that is all too common in the area, we’ve been advised to make sure children get enough fat in their diets.
This piece of advice came about as a result of a study published in an on-line in the Nutrition Journal . In this study, the body’s ability to metabolise or ‘burn’ fat was assessed in children (average age 8.7 years) and adults. Fat burning in the body was assessed by measuring something known as the ‘respiratory quotient’ of the study participants. This measurement, obtained by analysing the relative amounts of oxygen used and carbon dioxide released by an individual, allows scientists to calculate the relative amounts of fat and carbohydrate metabolized in the body’s cells.
Respiratory quotients (RQs) vary between 0.7 and 1.0. In theory, if an individual were to burn nothing but sugar, their respiratory quotient would be 1.0. Someone metabolising nothing but fat would have a respiratory quotient of 0.7. Basically, the lower the RQ is, the more fat is being metabolized relative to sugar.
Now on to the results of the study. What was found was that children, basically, had lower RQs than adults, and consequently, the relative amount of fat metabolized by children was higher too. So, logic dictates that kids can cope better with fat than adults, and therefore parents should not be concerned about including fat in their diets.
This is music to my ears. However, I feel compelled to add that the type of fat a child (or adult) eats can have an important bearing on health. A couple of types of fat worth getting out of the diet are what are known as processed, partially hydrogenated and industrially produced ‘trans’ fats. This particular brand of fat has been linked wilth all manner or ills including heart disease and some forms of cancer.
Other than that I take a quite relaxed attitude to fat, even saturated fat, found naturally in the diet. Despite repeated concerns about this form of fat, the evidence suggests this form of fat is benign at worst, and may actually have some benefits for the body. This is all discussed fully and scientifically referenced in my book The True You Diet.
Another point I make in this book is that respiratory quotients vary from person to person. Not just between young and old, but between people of similar age. And what this essentially means is that different people have differing ability to metabolise fat (or carb). Scientists have even gone so far as to attempt to dissect what might be responsible for these differences.
It has been found, for instance, that individuals with high respiratory quotients tend to be low in an enzyme called lipoprotein lipase  that has a role of in the breaking down of fat in the body, which is clearly essential for it to be ‘burned’. Another enzyme important for the metabolism of fat goes by the name of beta-hydroxyl acyl Co A dehydrogenase. Those with higher respiratory quotients have generally lower levels of this substance too .
These findings clearly have an important bearing on what would represent an individual’s ideal diet. All of this, is explored fully in the book, along with a questionnaire designed to discern what sort of foods are going to meet a individual’s nutritional requirements most fully.
I think the message for parents not to be too neurotic about feeding their kids fat is a hugely positive one. I also think that the study should remind us though, that our dietary requirements are not the same. Tailoring the diet to one’s nutritional needs is important if we are going to achieve optimal health and wellbeing.
2. Ferraro RT, et al. Relationship between skeletal muscle lipoprotein lipase activity and 24-hour macronutrient oxidation. J Clin Invest 1993;92: 441-445
3. Zurlo F, et al. Whole-body energy metabolism and skeletal muscle biochemical characteristics. Metabolism 1994;43:481-486