The Reinforcing Value of Added Sugars

Despite the long-term emphasis on reducing intake of and added sugar, this behavioral change
has been hard to instill amongst most of the population. Foods with added sugars are highly
reinforcing and, as such, reducing their consumption in order to adhere to the dietary
guidelines (DGA) may be difficult to maintain. Sugar produces effects similar to some drugs
of abuse such as increased extracellular dopamine release in the nucleus accumbens shell
resulting in a reinforcing effect. Reducing any reinforcing behavior can be challenging, but
in terms of food, it is not known whether the reinforcing value of foods high in added sugar
increases when access to these foods is reduced. If so, this would present a mechanistic
barrier to meeting the DGA and making dietary changes in general. That the reinforcing value
of a behavior (e.g., eating sugar) will be increased when the rate of that behavior is
decreased has strong theoretical underpinnings in the "Disequilibrium Approach". This theory
predicts that the circumstances of reinforcement are created or limited by changing baseline
access. According to the Disequilibrium Approach, a response deficit will result in an
increase in reinforcement. Applied to the proposed study, the Disequilibrium Approach would
predict that lowering the consumption of dietary added sugar would increase the reinforcing
value of foods high in added sugar. The Disequilibrium Approach has accurately predicted an
increase in the relative reinforcing value (RRV) of snack foods among children. However,
dietary changes would need to occur at the whole diet level for adults and children to meet
the DGA for reducing added sugar intake. It is important to know if reducing added sugars at
the whole-diet level results in increases in the reinforcing value of foods high in added
sugars.

Inclusion Criteria:

- BMI within 18.5-24.9 kg/m2 or BMI within 30.0-50.0 kg/m2

- Willing to consent to study conditions

- Habitually consume at least 10% of daily energy intake from added sugars

Exclusion Criteria:

- BMI 25.0-29.9 kg/m2

- Currently taking drugs that change hunger

- Have an eating disorder

- Current tobacco user

- Have diabetes or heart disease

- Pregnant, lactating or planning pregnancy

- Low liking of all available study test foods

- Allergy/aversion to any of the foods provided during the diet intervention