Vigorous workouts reduce hunger, especially in women – study
Higher intensity workouts appear to cause the suppression of the hunger hormone. Photo: Getty
You’d imagine that after an intensive workout – going all out, muscles straining, heart hammering – you’d be craving a snack.
And maybe you do – but it could be those cravings aren’t overly intense.
The more we look at hunger, exercise and metabolism, the more paradoxical the relationship seems to be.
A new study has found that high-intensity exercise actually suppresses hunger – and it does so more than a moderate-intensity workout.
The effect was more pronounced in female participants. The authors suggest more investigation is needed “on how biological sex may impact exercise and hormonal responses”.
Maybe. But the study was very small: Eight healthy male participants with an average age of 43, and six healthy female participants with an average age of 32.
The focus of the study, from the University of Virginia, was the effect of exercise on ghrelin, also known as the “hunger hormone”. This is because it signals to the brain to eat – but that signalling is complicated by the hormone’s other roles.
Past studies have shown that exercise may help subdue ghrelin levels, supporting the main finding of this new research.
What is ghrelin?
- Ghrelin which is produced in the gut and signals to the brain when a person is hungry. Hence the nickname ‘hunger hormone’. Ghrelin regulates both short-term energy balance, through appetite control, and long-term, through changes in body weight.
- Leptin is produced in your body’s fat cells. It’s often referred to as the ‘satiety hormone’ because it signals to the brain that you’re full.
In short, leptin decreases your appetite, while ghrelin increases it.
Ghrelin has several other functions, including pituitary gland secretion, insulin regulation, and reward-based behaviour. Indeed, ghrelin is thought to play a part in hedonic eating, where people consume food for pleasure as opposed to necessity.
Animal studies have found that supplemental ghrelin led to an increase in sexual behaviour. More research is necessary to assess whether the same is true in humans.
Unfortunately, ghrelin and leptin will thwart, or at least make difficult, your attempts to lose weight by restricting your diet.
During a weight loss diet, your ghrelin levels rise, increasing your appetite. Meanwhile, your leptin levels drop, and your feelings of fullness decline. This is the body trying to protect you from starvation.
A 2020 study that focused on people with type 2 diabetes found that a rise in ghrelin levels was significantly involved in stimulating appetite, making it harder to lose weight.
Exercise boost
Many people aren’t able to engage in high-intensity exercise, at least not for any length of time.
However, picking up the pace or putting the body under stress in short bursts (such as climbing stairs) can burn 20 to 60 per cent more energy than sustained activity for the same distance.
That’s the main finding of a study published this month at the University of Milan.
The researchers concluded that “by starting and stopping activity, the participants were able to expend more energy due to the metabolic processes that the body encounters while ramping up to strenuous bursts versus the sustained energy use of longer bouts”.
Again, this was a very small study: There were just 10 participants with an average age of 27 who were subjected to 10- to 240-second bursts of treadmill walking or stair-climber rounds.
Would this be enough to dampen ghrelin? We need another study to find out.
