Do you ever wonder why you find food repulsive after weight training or are starving after a long yoga class or walk on the treadmill? I have been battling this question for years, concluding that I just wasn’t eating enough if I felt hungry after a workout. However, this assumption never added up because no matter what time of day I exercise (morning on an empty stomach) or evening after having breakfast and lunch, my workout will always deem varied results. The culprit of the food cravings you face come from two hormones – those confusing messages our adrenal glands send out that we have so much difficulty understanding – Leptin and ghrelin.
Leptin is a hormone made by fat cells, that decreases your appetite. Ghrelin is a hormone that increases appetite and also plays a role in controlling body weight.
Leptin is the appetite suppressor, and lower levels correlate with lower body weight, versus higher levels resulting in obesity. This hormone signals to the brain that the body has enough energy stores (body fat) to avoid overeating. However, studies have found that obese patients do not respond to leptin’s signals even though they have higher levels, which makes it difficult to regulate body weight.
Leptin acts as a mediator of long-term regulation of energy balance, whereas ghrelin is a fast acting hormone, playing a role in meal initiation. Research also points to diets higher in good carbohydrates (whole grains, starches) to aid in ghrelin suppression more effectively than diets higher in fat. One study demonstrated these results after only three days on a high fat diet!
Hormones and exercise
Studies have shown that low to moderate aerobic activity (i.e. walking or running 30 to 60 minutes every day, yoga, or barre) increases ghrelin and decreases leptin - the opposite of what you want! The good news is that bursttraining workouts (think HIIT, boot camp fitness, 30- second sprints, etc. will lower ghrelin levels and conversely suppress your appetite), proving that for effective weight loss with lifelong results, simply walking on a treadmill every day (the most boring exercise in my opinion) just won’t do.
How to control hunger hormones
Studies show that getting enough sleep will suppress levels of ghrelin. Meaning, if you are depriving yourself of sleep (the best medicine for immunity, energy and overall health), you are increasing your hunger level compared with someone who is regularly sleeping 10 hours a night. A brief note on sleep: everybody varies on how much sleep they require to feel rested, but the majority of people require at least 8 hours. If you are getting any less than that, you are lying to yourself about feeling “fine”. When the body isn’t well rested, it requires more energy to push through the day, which is where the sugar and caffeine cravings kick in – especially in that midafternoon slump around 3 or 4 pm. This is also when many people feel lethargic and make unhealthy food choices. My advice for if you had a bad night’s sleep is to drink lots of water and power through the cravings until dinner. Drink herbal teas and non-caffeinated liquids (lemon water, perhaps?) and have a lot of water rich foods for dinner – raw vegetables, coconut water, etc.
Studies show a direct link between stress levels and the release of ghrelin into the blood. That is why stress eating is a thing and so many people do it. How to combat stress? You can find plenty of information about meditation on my blog. You can also try journaling, taking a hot bath, adopting an adaptogenic mushroom routine (starting with your morning coffee), or reading before bed instead of using social media.
This is just the start
People who have suffered from disordered eating and yo-yo dieting have most often deregulated their hormones which leads to many issues including thyroid problems, adrenal fatigue and PCOS. In these instances, the hunger hormones will also be out of balance making it difficult to determine physical hunger from lethargy or eating out of boredom. This is also the reason that people find themselves binge eating on foods after a period of calorie deprivation. Research on hormones and the adrenal system is still very limited, but scientists are currently working on pills to treat obesity using these hormones. In the mean time, at least you have answers on how to determine hunger signals and choose exercise wisely.