ACHIEVE AND MAINTAIN A HEAlTHY WEIGHT
19Guideline 1
Evidence statement Grade
Babies born to mothers who smoke during pregnancy are at an increased risk of development of overweight or obesity in
adolescence and adulthood. B
Combined diet and physical activity interventions are associated with reduced risk of overweight and obesity in children. C
Combined diet and physical activity interventions are associated with reduced risk of overweight and obesity in adults. C
Consumption of vegetables is associated with reduced risk of weight gain. C
Consumption of fruit is associated with a reduced risk of obesity and weight gain. C
Hours spent watching television by children is associated with increased risk of development of overweight or obesity. C
In developed countries, a low family income or socioeconomic status is associated with increased risk of overweight or obesity
during childhood, adolescence, and young adulthood.
C
Low socioeconomic status is associated with an increased risk of overweight or obesity. C
Interventions delivered in the school environment that are focused on eating and physical activity improve weight outcomes
in children. C
Notes: Grades – A: convincing association, B: probable association, C: suggestive association
Includes evidence statements and gradings from the Evidence Report (literature from years 2002–2009). Does not include evidence from
other sources, such as the 2003 edition of the dietary guidelines (in which individual studies were classified according to their design as
level I, II or III but overall grades for relationships were not derived), although these sources have been used to inform these Guidelines.
Grade C evidence statements showing no association and all Grade D statements can be found in Appendix E.
1.2.1 Primary and secondary prevention
Favourable outcomes have been consistently observed in interventions focusing on both reduced energy intake
and increased physical activity, supporting the evidence statements that combined interventions assist weight
management in children, adolescents and adults.
• Adults: There is evidence that diet and physical activity interventions in adults can prevent overweight and
obesity (Grade C; Evidence Report, Section 22.2).^171 lifestyle interventions combining diet and physical activity
interventions are probably associated with reduced risk of developing type 2 diabetes in adults (Grade B;
Evidence Report, Section 22.3).^171 For further information, see the NHMRC Management of overweight and
obesity in adults, adolescents and children (NHMRC Overweight and Obesity Guidelines).^121
• Children and adolescents: Recent reviews of combined diet and physical activity interventions for children and
adolescents suggest that these can prevent overweight and obesity (Grade C; Evidence Report, Section 22.1).172-
(^175) There is convincing evidence that behavioural interventions including diet and physical activity reduce the risk
of obesity in overweight children – these interventions are more effective when they are family-based (Grade
A; Evidence Report, Section 17.12).176-179 Recent evidence suggests that interventions delivered in the school
environment that focus on healthy eating and physical activity improve weight outcomes in children (Grade C;
Evidence Report, Section 17.1).180,181 There is a limited amount of quality data on specific components of the
combined programs in treating overweight and obesity; however, the results of combined programs indicate
significant and clinically meaningful reductions in the level of overweight in obese children and adolescents.182,183
1.2.2 Dietary patterns and specific foods and drinks
There is increasing evidence that consumption of specific foods and food groups is associated with risk of excess
weight gain, while other food types are associated with a reduced risk of weight gain.
• Fat: The 2003 edition of the dietary guidelines and many international public health organisations, including
the World Health Organization (WHO),^98 emphasised the major role of fat consumption in the development of
overweight and obesity and of reducing fat intake as part of management. More recently, WHO has shifted
its emphasis, stating that there is convincing evidence that energy balance is critical to maintaining healthy
weight and ensuring optimal nutrient intakes, regardless of macronutrient distribution.^184 Although no specific
macronutrient may be responsible for the development of obesity, the proportion of macronutrients in the diet
does influence energy and nutrient intake, which may impinge on weight management and health outcomes.