Dr. D. A. Cassuto and Dr. M. L. Frelut

Child obesity is becoming a common public health concern in all industrialised countries.
Genetic factors are certainly involved in its development, along with the lack of energy expenditure and an excessive or unbalanced food intake. It is the role of physicians to propose specific answers for the treatment of each case.

Child obesity is rapidly growing in industrialised countries. Genetics only seems to account for one third in its onset, whereas environmental factors such as food, physical activity or psychosocial factors trigger the deleterious expression of an unfavourable genetic predisposition. Childhood is therefore a key period to prevent and treat obesity.

Body mass index (BMI : weight/height2) is used to establish the diagnosis of obesity: obesity is identified beyond the 90th percentile of reference curves. In children, obesity is considered severe beyond the 97th percentile (Figure 1). Since 1997, these curves now appear in medical reports.
If the prevalence of obesity remains higher in the USA than in Europe, the situation is unfortunately rapidly spreading in France. The number of very obese French children at age ten went from 3% in 1965, to 12% in 1995, with geographical variations. A similar evolution is also observed for other periods of life. (Figure 1).
Two epidemiological studies have showed, 40 years later, the risk associated with the only fact of having been obese during adolescence: higher vascular mortality and cancer, especially colon cancer in both genders and breast cancer in women.
The majority of child and teenager obesity is considered as primary obesity: indeed, very seldom is obesity associated with pseudohypoparathyroïdism, hypothyroidism, growth hormone deficit, Willi-Prader syndrome, or even related to a cerebral tumour.

A medical consultation is an essential moment: it must be specific to the obesity problem and include an interview with parents and another one with the child. Providing advice on an obesity problem at the end of a consultation sought for other symptoms often leads to guilt and dismissal on behalf of the child.
The interview must identify the following: child's motivation, family history of obesity, inactivity level (television, computer), sports activity in and out of school, sleeping patterns, child care outside of school, transportation to school, amount and habits of food consumption. All these information can be collected in several meetings. Encouraging the child to fill a habit diary allows him to play an active role in the process and to identify his motivation.
Measurement of weight and height is better accepted by the child if he is alone and results must be compared to reference curves. The simple fact of keeping the same silhouette, i.e. of not slenderising by the age of six, corresponds to the development of an "early adiposity rebound" obesity. If these curves are not drawn, diagnosis of obesity is often delayed for several years.
A clinical examination must identify complications such as vergetures, arterial hypertension, articular pains or dyspnea under effort, associated pathologies, or a small height. From the age of ten, especially in girls, it is essential to assess puberty stage. Onset of puberty has a different impact on boys and girls. Whereas in boys, fat mass decreases by about 4% because of a synergetic effect of testosterone and leptin, it increases in girls. However this modest physiological variation can not solve an important drift in obese boys, and in girls the evolution is altogether unfavourable. It is therefore unjustified to expect that growth and onset of puberty will cure obesity per se, although intellectual maturity reached at puberty facilitates the dialogue and the help provided by the physician.
In young girls, excess in fat mass can induce signs of puberty. In case of a tall girl, determining bone age allows to identify the degree of growth in relation to statural age.

Although the physiological process of atheromatosis is inherent to ageing, there is a large variation in cardiovascular risk because of the interaction between genetic predisposition and environmental factors. The ideal preventive measures would quantify individual cardiovascular risk and identify subjects responding to dietary intervention. At present, a family history of hypercholesterolemia or hypertriglyceridemia, or even a slight increase in LDL and/or triglycerides are as many formal indicators to follow a preventive diet from the age of 40.

Cardio - respiratory complications
Restrictive respiratory syndrome is correlated to the severity of obesity, and is sometimes associated with asthma. Functional respiratory tests will differentiate between these two pathologies. The interview should contribute in detecting sleep apnea.

Metabolic and endocrine complications
Insulin resistance is a precocious complication of child obesity whereas non insulin-dependent diabetes is exceptional. In presence of the slightest obesity in a child, a lipid profile must be done to detect an obesity-related dyslipidemia. In general, in child and teenage obesity, cholesterol and triglyceride levels measured on an empty stomach are within normal values. Hypercholesterolemia or hypertriglyceridemia may identify the coexistence of two distinct pathologies, elevating the risk of cardiovascular problems.
Presence of purple vergetures is frequent in severe obesity: it is a sign of consequent hypercorticism that will disappear with weight loss. An adrenal gland defect must be ruled out at the slightest doubt.

Orthopaedic complications
The most serious complication is slipped capital femoral epiphysis and occurs at around ten years of age: it is eight times more frequent in the obese children. In severe obesity, femoro-patellar syndrome is frequent from the onset of adolescence. Diagnosis of Osgood-Schlatter disease must not lead to the elimination of sport activity, but to the choice of an appropriate physical activity.

Evolution of the prevalence of child obesity in different regions of France
Region	Diagnostic criteria	Age	Year of survey	Obese (%)
Lorraine (1)	P/T² > 97,5ème centile	4-17	1980 1990	2.5 3.2
Languedoc (2)	Z-score P/T² > or = 2	4-5	1987-1988 1992-1993	1.8 4.9
Centre (3)	P/T² > or = 25 kg / m² P/T² > or = 20 kg / m²	9-10 9-10	1980 1996 1980 1996	0.4 1.9 5.1 12.7

Nutrition
Few studies report a much higher food consumption in the obese children than in thin children, except for massively obese children. Some studies underline the role of new eating patterns and snacks in the onset of obesity. On the other hand, compared to non-obese, obese children like less diverse foods, and have therefore a less varied nutrition. Qualitative and quantitative estimation of food intake often helps to identify possible family habits and those proper to the child.

Physical activity
Insufficient physical activity characterises the vast majority of obese children. The environment plays an extensive role here: spaceless, more or less safe cities and parents absent for long periods of time considerably diminish the opportunities for children and teenagers to release their energy, in addition to the insufficient hours of gym classes in school. Physical difficulty and suffering from mockery contribute to the onset of a vicious circle: avoidance of a painful situation and boredom leads to more snacking and weight gain. Maintenance or even rediscovery of a normal social life for each age is the key element of prevention and treatment of child and teenage obesity.
The role of television and electronic games is ambiguous: chosen in part by interest, they are a makeshift alternative to inaccessible outdoor games. While watching television, the energy expenditure falls to the lowest levels such as during sleeping.

Therapeutic strategy
Diet should not eliminate any food in particular, and should take into account age, gender and physical activity level. The involvement of parents will focus on meals eaten at home; the child must learn to manage his boredom, often the cause of snacking. The physician will help families to keep up in front of difficulties by encouraging a non-guilty self-criticism of family food behaviour and solidarity.
The choice of physical activities and sports will take in account their psychological and socio - cultural aspect as well as their orthopaedic risks.
Parents are often a lot more hurried than the child, to whom the physician must explain the benefits of weight loss: growing without fattening, that is the goal! Follow-up is essential for motivation. In cases of severe obesity, treatment in a specialised centre may be considered. It should not exclude parents nor family physician who will then have to help the child to pursue his efforts. In certain cases, a psychological treatment is necessary.

PSYCHOSOCIAL ASPECTS OF CHILD OBESITY
	It is necessary to know the family and school environments of an obese child and to assess the psychological difficulties he is encountering, consequent or not to his obesity problem. A personal or family event often occurred during the period preceding the onset of weight gain. In most cases, an obese child has suffered mockeries from a very early age. It is therefore important to distinguish between psychological consequences of obesity and its possible related causes. Psychiatric condition of the child will determine the possibilities for nutritional intervention. According to a Danish study academic failure occurs 4 times more often in obese children. Other studies identify an additional risk of obesity in cases of a unique child, a youngest child, or a single parent family. Social factors and role of the environment often adds up, in particular in large cities. Still according to the Danish study, the area where a child lives is the major social determining factor of obesity risk during adulthood, after his family social status.

Obese children have the same taste than non-obese children for high caloric density foods. Obesity that starts during childhood is due to the interaction between an unbalanced food behaviour and environmental factors. A child is not a miniature adult needing an elaborate calorie-reduced diet. There is not a unique answer to always-different situations.

Dr. D.A. CASSUTO
Hôtel Dieu, Paris,

Dr. M.L. FRELUT
Robert Debré Hospital, Paris,
Paediatric Therapeutic Centre.