That frustrating moment where you're doing everything right - eating like a saint, exercising like a Trojan - but STILL not shedding the KGs. As a study published in the Journal of Endocrinology found, the key to slimming down your waistline could lie in a hormone called ghrelin which regulates your appetite.

The study recruited 16 healthy, fit young men (they did not include women because this was a small, pilot study, the authors say, and controlling for the effects of women's menstrual cycles would have been difficult.) Participants were split into two groups: One group focused on intensity, ranging from an easy jog for 55 minutes (50% of their maximum capacity) to a more vigorous pace for 36 minutes (75% of maximum capacity), until they burned around 600 calories.

The second group focused on length with a run for 45 minutes at a steady pace on one day, followed by a run for 90 minutes at the same pace on another day (70% of maximum capacity). Throughout the experiment, both groups ate standard meals.

Results reveal that our appetites certainly are strange, influenced by many factors beyond hormones and burning calories. In general, exercise lowered ghrelin (making people less hungry) with the effects being more pronounced when runs were vigorous (above 75% maximum capacity) and longer (90 minutes) compared to gentler jogging or briefer runs (45 minutes).

Interestingly, hormones remained suppressed one-hour post workout when workouts were the longest. What's more, those who ran for 90 minutes reported feeling less hungry compared to those who carried out short, intense workouts, who soon felt peckish, despite still having low levels of ghrelin in their blood.

So, what does this mean?

The longer and more intense your workouts are, the lower your levels of grehlin. With less grehlin pumping through your veins after hitting the gym, you will stick to your meal plans and avoid unnecessary bingeing. Remember exercise has many other benefits irrespective of weight loss: elevated mood, immune boosting, reduced blood pressure, and improved fitness, to name a few.

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