This article was written for DiabetesSA and is also featured on their website.
Hunger is often seen as the enemy and therefore by association the hunger hormone, ghrelin, is demonised and ostracized.
The name Ghrelin doesn’t do itself any favours though, as it sounds like a gremlin. The Oxford dictionary even defined gremlins as:
- In early use: a lowly or despised person; a menial, a dogsbody, a wretch (obsolete).
- Later: a mischievous sprite imagined as the cause of mishaps to aircraft.
- More generally: such a creature is imagined as the cause of any trouble or mischance.
- Hence also: an unexplained problem or fault.
But let us take a closer look at this misunderstood and underappreciated hormone.
Hormones that control appetite
A host of hormones—insulin, leptin, adiponectin, and ghrelin, among others—communicate with the brain’s control centre called the hypothalamus to manage a person’s intake and weight. These regulatory hormones regulate feeding in response to signals from body tissues.
- Insulincontrols the amount of glucose in the blood by moving it into the cells for energy.
- Leptin, which is produced mainly by fat cells, contributes to long-term fullness by sensing the body’s overall energy stores.
- Adiponectin is also made by fat cells and apparently helps the body respond better to insulin by boosting metabolism.
- Ghrelin, the hunger hormone, is produced primarily by the stomach and tells the brain when the stomach is empty, prompting hunger pangs and a drop in metabolism. Ghrelin also increases our cravings and affinity for sugar- and carbohydrate-rich foods (which is a problem for glycaemic control).
This communication of the stomach with the brain happens via the vagus nerve, part of the autonomic nervous system that travels from the brain to the stomach. When filled with food or liquid, the stomach’s stretch receptors send a message to the brain indicating satiety.
Weight-loss and Ghrelin
It seems easy enough then to lose weight, right? There should just be a drop in ghrelin levels.
Unfortunately, it is much more complicated than that. Ghrelin levels are highest in lean individuals and lowest in the obese. Increased levels are seen in people who are dieting. In fact, traditional dieting tends to boost ghrelin levels.
The reasons for this can be debated until the end of time but my short and not at all in-depth explanation is to always remember that our bodies try their utmost best to protect us and keep us alive and safe. In the case of ghrelin, the real threat and danger we are being protected from is starvation.
So, what can we do then? How can we tame the hunger hormone? It is also worthy to mention at this point that interfering with hormones can be extremely dangerous, therefore we would be looking at lifestyle factors instead of hormone-altering treatments.
Lifestyle factors that affect Ghrelin
Low concentrations of glucose in the blood showed an increase in ghrelin secretion, however interestingly though – insulin was also shown to affect ghrelin levels (which might seem contradictory if we understand the link between glucose and insulin production). Further research is needed to fully understand the link, but from what we know now is that instead of the insulin itself the insulin-sensitivity might be more important to regulate ghrelin levels.
Regular meals that are high in fibre and low in glycaemic index, that provide a slower release of glucose into the bloodstream is recommended.
The connection between protein and ghrelin is less clear. One study found that the ingestion of essential amino acids leads to a continuous rise in serum ghrelin levels, which unexpectedly contradicts other studies that found an inhibitory effect of protein on ghrelin.
Although the connection isn’t clear, adding healthy lean proteins are always beneficial for meals to be more balanced.
Healthy fats also helped reduce the ghrelin levels in the plasma. Thus adding healthy fats to your meals as well are recommended as well. Foods that contain omega 3 like fatty fish, chia and flax seeds and nuts will boost leptin and keep ghrelin in check.
Total ghrelin level increases at night and decreases after breakfast in humans. Circulating ghrelin concentration rises before a meal and falls after a meal and serum ghrelin increases steadily during long term of fasting in humans. Eating regular meals and snacks per day will keep ghrelin and leptin levels stable. During crash dieting or calorie restriction, ghrelin levels increase and poor food choices and cravings will increase.
Therefore, fasting is not recommended and regular balanced meals are better for ghrelin-regulation.
Good quality and uninterrupted sleep:
There have been numerous studies showing the importance of good quality sleep on weight loss and maintaining a healthy weight. Participants with less than 7 hours of sleep were shown to have higher BMI’s and were thought to have increased appetites. The mechanism of leptin and ghrelin might explain those results. To gradually reduce ghrelin, aim for 7-9 hours of sleep each night.
As stress levels get elevated, ghrelin levels tend to increase (hallo sugar cravings during stressful times?). Circulating ghrelin levels have been found to rise following stress. It has been proposed that this elevated ghrelin helps the animals in the study to cope with stress by generating antidepressant-like behavioural adaptations, although another study suggests that decreasing the central nervous system ghrelin expression has antidepressant-like effects.
Engage in activities that help you to rest and relax – spending time outside in nature, engaging in exercise you enjoy, arts and crafts that help you be creative and lastly get feelings off your chest and allow yourself to feel and heal your emotions.
In conclusion, to take everything together:
- The hunger hormone is called ghrelin.
- Ghrelin is not the enemy; it is made to protect your body and protect you against starvation.
- Traditional dieting and fasting tend to upregulate ghrelin levels.
- Fasting is also not recommended as it also tends to increase ghrelin levels.
- Ghrelin levels can be modulated by:
- Eating a balanced diet with sufficient complex and low glycaemic index carbohydrates, healthy fats and lean proteins.
- Ensuring regular and adequate meals to prevent hypoglycaemia.
- Aim for 7 – 9 hours of sleep per night. Good, uninterrupted sleep is very important.
- Reducing stress levels in any way that feels good for you.