Histamine Affinity, Orexigenic Load and Thermogenesis By Prof Roger Chen

Posted on: May 28, 2020
Last Updated: October 13, 2020

Associate Professor and Endocrinologist, Roger Chen is Director of Diabetes Services and Senior Staff Specialists in the Department of Endocrinology and Metabolism in Concord Hospital, Sydney. His clinical interests are in general endocrinology, osteoporosis, and diabetes. His research interests include diabetes prevention, diabetes complications, and the relationship with mental illness.   

Author Quotes 

It’s interesting that these drugs seem to have some differential effects…these drugs are incredibly diverse in their action and mechanisms; they work on dopamine systems, histamines, etc.

It’s those [drugs] with the highest histamine receptor affinity which are associated with the greatest amount of weight gain.


Prof Chen begins this video excerpt with a look at the effect of different antipsychotic drugs on weight gain and measured visceral fat. He also explains about the association between orexigenic load and weight gain. 

He continues with a discussion on some elegant animal studies; one study in rats (olanzapine and clozapine) seemed to indicate there was an induction of whole-body insulin resistance, and the other study in mice (olanzapine) found that even though two groups (olanzapine vs placebo) had the same amount of food, the olanzapine mice gained more weight. 

The presentation concludes with a discussion of thermogenesis and some questions from the audience.

Take-Home Points  

  • GLP-1 receptor agonists are associated with significant weight loss. 
  • The mechanism of GLP-1 agonist weight loss may be due to loss of appetite but this is unknown. 
  • SGLT2 inhibitor drugs do not work on appetite; weight loss is an independent effect through a loss of calories, but weight gain may resume on reaching target weight loss. 


Learn more 

  1. The Obesity Epidemic – Professor Roger Chen
  2. Psychiatric Medications and Weight Gain – Prof Roger Chen
  3. What is Diabetes? By Professor Roger Chen
  4. Metabolic Profile in Psychiatry By Prof Roger Chen