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Hormones

How hormones steer our appetite and eating behaviour

Flowing through your blood are chemical messengers that help to control your appetite. Understanding how they work can shed the light on the role of biology in weight regulation and explain why interventions that work to address underlying biological processes are needed to effectively treat obesity.

5 min. read
Contented young woman with eyes closed, embodying balanced eating habits and satisfaction

We do not decide to be hungry or full after a meal, do we? We just feel either one of those sensations in a due time and then proceed with relevant actions.

Nor can we comprehend why we prefer a chocolate bar over a green apple for a late afternoon snack, when in the morning we firmly intended to persevere with healthy choices.

So, if our eating behaviour and food choices are not entirely in our conscious control and sometimes run counter to our intentions, what are the other forces at play, how do they work, and why do they often seem to ruin our plans?
 

Chemical messengers make us feel hungry or full

“The need to find fuel to generate energy is a profound drive within the biology of all living organisms: we all need food to survive. So, it’s not surprising that our bodies have such a complex system to control food intake, driven by hormones,” explains Joseph Proietto, professor of medicine at University of Melbourne

It appears that hormones act like chemical messengers between the body and the brain that coordinates our eating behaviour and food choices.

These hormones circulate in the blood and come from tissues in various parts of the body that deal with energy intake and storage, including the gut (which receives and digests food), fat tissue (which stores the energy as fat), and the pancreas (which makes hormones that are involved in energy storage, such as insulin).

“The need to find fuel to generate energy is a profound drive within the biology of all living organisms: we all need food to survive. So, it’s not surprising that our bodies have such a complex system to control food intake, driven by hormones.”

-Professor Joseph Proietto, University of Melbourne

Some hormones, are responsible for stimulating hunger (let’s call them “hunger hormones”) while others responsible for making us feel full (let’s call them “satiety hormones”).

Once full, the stomach reduces our desire to eat by producing less of the hunger hormone and sending a message to the brain to make us stop eating. At the same time, the levels of satiety hormones increase following a meal and reach a peak between 30 and 60 minutes later.

This dynamic interplay, helps our brain to regulate our eating behaviour. Another set of hormones can steer our food choices and motivate us to eat, even in the absence of physical hunger.
 

How weight loss affects our hormones

It seems that hormone levels also change when we lose weight. Several studies have found that diet-induced weight loss is associated with hormonal changes that promote weight regain.

Following weight loss, levels of satiety hormones decrease and levels of hunger hormones increase. These changes lead to a persistent increase in hunger, reduced feelings of fullness and burning fewer calories. These changes may last for up to three years and are probably part of the reason why 8 out 10 people end up regaining lost weight in the long run.

These findings suggest that suppressing hunger after weight loss, may help people to maintain their new weight.
 

Following weight loss, levels of satiety hormones decrease and levels of hunger hormones increase. These changes lead to a persistent increase in hunger, reduced feelings of fullness and burning fewer calories.

-Hall KD & Kahan S., Maintenance of Lost Weight and Long-Term Management of Obesity

Working around your hormones

While we cannot control our hormones, understanding them is key in how to stop being hungry unnecessarily. When we feel hungry, it is very hard not to eat – no matter how much we might not want to. But learning how our hormones influence our eating habits can help us understand the necessary interventions and strategies for effective weight management.

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Metrics Imperial
Metrics / Imperial
References
  • Proietto J. Chemical messengers: how hormones make us feel hungry and full. The Conversation 2015: https://theconversation.com/chemical-messengers-how-hormones-make-us-feel-hungry-and-full-35545 [Accessed July 2019].
  • Berthoud HR, Münzberg H, & Morrison CD. Blaming the Brain for Obesity: Integration of Hedonic and Homeostatic Mechanisms. Gastroenterology 2017; 152:1728–1738.
  • Hall KD & Kahan S. Maintenance of Lost Weight and Long-Term Management of Obesity. Med Clin N Am 2018; 102:183–197.
  • Purcell, K et al. The effect of rate of weight loss on long-term weight management: a randomized controlled trial. Lancet Diabetes Endocrinol 2014; 2:954-962.

February 2024; IE23OB00174

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