Irregular eating and poor food choices may be leaving your son rundown with no energy. The best way to improve his eating habits is to get good information on healthy eating. The Biggest Loser Families book contains basic information on the core foods groups from the Australian Guide to Healthy Eating along with serve size information and rough estimates of the number of serves needed per day. It also has a table that tell you which foods are good sources of important nutrients to keep your body healthy along with the functions of these nutrients in your body.

Active teenage boys in particular need a lot of food to keep them fuelled and healthy. For example this can include up to 11 serves of breads and cereal, 5 or more serves of vegetables, 5 serves of dairy products, 2 serves of lean meat, fish, poultry and vegetarian alternatives such as eggs, nuts and legume.

As a parent, it is really important you give your child the information they need on about health eating. For great information go to the “Smart Eating for You” page of the Dietitians Association of Australia website.

If your son continues to be lacking in energy and is eating healthy food that includes lean meat as a good source of iron, then ensure he has a check-up with your GP to rule out other causes.

Are you Australia's healthiest eater? Try the Healthy Eating Quiz developed by the School of Health Sciences in the Faculty of Health at the University of Newcastle.

Dr Clare Collins is a Professor in Nutrition and Dietetics at the University of Newcastle and consultant for The Biggest Loser