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), 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. 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.
Sugar:
No large long-term studies have measured the long-term development of overweight or obesity specifically related to consumption of added sugars . However, recent evidence indicates that it is probable that consumption of sugar-sweetened drinks (soft drinks) is associated with increased risk of weight gain in adults and children a finding confirmed by a later longitudinal study.
Sugar-sweetened drinks:
The literature review to inform the revision of the Dietary Guidelines for Americans, 2010 found strong evidence that greater intake of sugar-sweetened drinks is associated with increased adiposity in children and moderate evidence that consumption of sugar-sweetened drinks is associated with increased body weight in adults. Most of the relevant research was conducted in the US where, unlike Australia, corn syrup containing fructose is commonly used to sweeten soft drinks. Although these sweeteners differ only slightly from those used commonly in Australia, this was taken into consideration in grading the relevant evidence statement.
Glycaemic index:
The US review found strong and consistent evidence that glycaemic index and/or glycaemic load are not associated with body weight and that modifying either of these does not lead to greater weight loss or better weight management. There is considerable variability in these indices, depending on inter-and intra-individual factors and the form of food (including the degree of processing, stage of ripeness, cooking and cooling times), which may limit practical application.
Vegetables and fruit:
There is evidence suggesting that consumption of vegetables is associated with a reduced risk of weight gain. Evidence also suggests that consuming fruit is associated with a reduced risk of obesity and weight gain. The US review found that the evidence for an association between increased fruit and vegetable intake and lower body weight is modest, but may be important in the long term.
Portion size:
The US review found strong evidence of a positive relationship between portion size and body weight.
Dairy foods:
Recent evidence suggests that consumption of dairy foods is not associated with weight change or risk of obesity and that consuming milk is not associated with BMI or BMI change in childhood. These findings are consistent with those of the US review, which found strong evidence that intake of milk and milk products do not have a distinct role in weight control.
Grains:
There is evidence of a probable association between consumption of three to five serves per day of grain (cereal) foods (mainly wholegrain) and a reduced risk of weight gain
Nuts:
There is evidence to suggest that consuming nuts (65–110g per day) is not related to risk of weight gain in the short term .
Fruit juice:
The US review found that, for most children, there was limited evidence that intake of fruit juice is associated with increased adiposity when consumed in amounts that are appropriate for the age and energy needs of the child. However, increased intake of fruit juice was found to be associated with increased adiposity in children who were already overweight or obese.
In seeking to achieve and maintain a healthy weight it is prudent to choose nutrient-dense foods of lower energy density – that is, those low in total fat, particularly saturated fat, and added sugars – in a total dietary pattern that seeks to control overall energy intake. The US review found strong and consistent evidence that dietary patterns that are relatively low in energy density improve weight loss and weight maintenance in young adults.