What About Oxytocin?

It seemed that Childhood Obesity News‘ examination of currently available weight-loss drugs had come to an end, but no. As it turns out, another hormone might be in the running. This news was revealed at the latest annual meeting of the Endocrine Society. It comes from neuroendocrinologist and associate professor of medicine Elizabeth Lawson, and colleagues at Harvard Medical School.

They already knew that oxytocin improves the body’s sensitivity to insulin and somehow encourages the use of fat as fuel. Olga Khazan wrote for The Atlantic,

Lawson’s other studies have shown that oxytocin reduces activation in the hypothalamus, an area of the brain that controls hunger, and increases activation in areas of the brain associated with impulse control. To Lawson, the results together suggest that the hormone creates less of a need to eat, reduces the compulsion to eat for fun, and improves impulse control when it comes to actually reaching for that second slice of cake. Oxytocin, in other words, appears to make food seem less rewarding.

More recently, in a very small study involving 10 overweight and obese men, the subjects were shown pictures of high-calorie foods. Consequently, “the regions of the brain involved in eating for pleasure lit up.” This comes under the heading of over-activation, because being stimulated to eat when the body does not actually need nutrition serves no useful purpose, and leads to damaging behavior. However,

A dose of oxytocin, compared with a placebo, weakened the activity in those regions, and it also reduced the activity between them. Meanwhile, oxytocin didn’t have that effect when the men viewed images of low-calorie foods or household items.

Apparently, oxytocin enhances the sense of being satiated, or full, which obviously helps to prevent unnecessary eating. However, and this is a problem with many experiments, it is not yet clear whether the brain over-activation causes obesity, or whether obesity causes the over-activation. So plenty of work is yet to be done. The numbers need to be bigger, and at least half the subjects need to be women. And yet, in laboratory rodent tests, when it comes to central oxytocin pathway gene expression, sex doesn’t seem to make a difference.

Or maybe it does

Here is a weird little result suggesting that there are sex differences:

[Researchers] also found that men who had been given oxytocin, compared to men who received the placebo, expressed a stronger desire to date women who had previously been unfaithful. There was no equivalent effect of oxytocin on the female volunteers, but oxytocin did increase women’s interest in long-term relationships with faithful men.

In short, oxytocin didn’t simply turn men and women lovey-dovey; instead, it promoted the pre-existing sex differences in men’s and women’s preferences for faithful and unfaithful partners.

Research from Oslo University Hospital indicated hope for using oxytocin to regulate appetite in humans. They also found that it influences cognition and social behavior, including the processing of social cues. Proficiency in these areas could mitigate a person’s basic reasons for overeating in the first place.

One of the problems with research so far is the delivery system best practice. Although nasal spray is very effective in keeping test subjects from discriminating between an active dose and a placebo, the researchers really have no way of knowing how much of the substance gets through to the brain.

Another problem is that like many drugs, oxytocin seems to work differently on different people at different times and for different reasons. In other words, it’s that old spoiler again, multifactorialism.

For instance, human obesity has many causes, including psychological ones. The particular, individual cause could influence the outcome, a lot. As always, one question would be, “But is it safe for long-term use?” Since the body itself makes plenty of oxytocin, the answer would seem to be yes — but you never know.

(To be continued…)

Your responses and feedback are welcome!

Source: “The ‘Cuddle Hormone’ Might Help America Take On the Obesity Epidemic,” TheAtlantic.com, April 2019
Source: “Oxytocin: More Than Just a “Love Hormone,” PsychologyToday.com, 02/20/19
Source: “Oxytocin pathway gene networks in the human brain,” Nature.com, 02/08/19
Photo credit: trendingtopics on Visualhunt/CC BY

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About Dr. Robert A. Pretlow

Dr. Robert A. Pretlow is a pediatrician and childhood obesity specialist. He has been researching and spreading awareness on the childhood obesity epidemic in the US for more than a decade.
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Dr. Pretlow’s invited presentation at the American Society of Animal Science 2020 Conference
What’s Causing Obesity in Companion Animals and What Can We Do About It

Dr. Pretlow’s invited presentation at the World Obesity Federation 2019 Conference:
Food/Eating Addiction and the Displacement Mechanism

Dr. Pretlow’s Multi-Center Clinical Trial Kick-off Speech 2018:
Obesity: Tackling the Root Cause

Dr. Pretlow’s 2017 Workshop on
Treatment of Obesity Using the Addiction Model

Dr. Pretlow’s invited presentation for
TEC and UNC 2016

Dr. Pretlow’s invited presentation at the 2015 Obesity Summit in London, UK.

Dr. Pretlow’s invited keynote at the 2014 European Childhood Obesity Group Congress in Salzburg, Austria.

Dr. Pretlow’s presentation at the 2013 European Congress on Obesity in Liverpool, UK.

Dr. Pretlow’s presentation at the 2011 International Conference on Childhood Obesity in Lisbon, Portugal.

Dr. Pretlow’s presentation at the 2010 Uniting Against Childhood Obesity Conference in Houston, TX.

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