Ghrelin - The Hunger Hormone

Hormones - Oestrogen and testosterone are the two that most likely spring to mind, and their role in puberty, libido, the reproductive system. In fact, our bodies produce a whole host of other hormones which play a role in our health and how we function day in day out. Ghrelin, given its name as a ‘growth hormone releasing peptide’, controls hunger, food intake and combined with growth hormone... FAT storage.

Stimulated by the cells in our stomach, ghrelin sends signals to the hypothalamus in the brain telling our bodies it’s time to eat. Small amounts are also released by the pancreas and the small intestine. The more ghrelin in the bloodstream, the bigger the appetite and likely, the more food you eat. After food, ghrelin levels are decreased as we’re satiated, and they don’t rise again until your body starts looking for more energy.

If you’re trying to lose weight, you might be wondering how you can keep your levels low. To be clear, ghrelin is not bad. Our hormones are made for a reason - they have a specific job to do in the body. If we weren’t ever hungry, would we take as much joy from the food we eat? How would we know when we’re low on nourishment? How would we function at our optimum?

It’s when they stop working as they should that we can run into trouble. And, our diet and lifestyle choices have a significant impact on this. That doesn’t mean jumping to calorie restriction. Naturally, this will increase your ghrelin levels, potentially lead to overeating and storage of fat. Interestingly, research has shown lower fasting levels of ghrelin in individuals who are overweight, obese or morbidly obese, this suggesting that over time, overeating can decrease sensitivity to the hormone, meaning we lose this essential control mechanism.

However, it’s important to note that ghrelin may be equally as important for weight gain. It’s all about balance.

So, we’ve highlighted a few tips here, which will help keep this specific hormone in check and doing its job correctly at both ends of the spectrum.

1 - Eat a diet rich in fibre from fruit and vegetables, legumes and wholegrains. Fibre slows down our digestion while also keeping our gut bacteria diverse and healthy. Foods high in fibre also tend to be lower in calories and higher in nutrient density meaning you get better bang for your buck when it comes to calorie intake.

2 - Limit intake of high GI carbohydrates and processed foods high in sugar and artificial sweeteners. Refined and processed foods are high in calories and saturated fat and low in nutrients. As well as spiking your blood sugar for a short period, sending your hunger and energy levels on a rollercoaster, they trigger release of dopamine, the neurotransmitter associated with reward. We start to associate that short lived high with reward as opposed to the feeling of being nourished and satiated.

3 - Eat protein with every meal. Incorporating a portion of lean or vegetable protein into each meal (eggs, oily fish, organic chicken or turkey, tofu, beans and pulses) will slow gastric emptying, keeping you fuller for longer. It will also blunt the insulin spike you get from eating a carbohydrate based meal, preventing the sugar cravings which inevitably follow that initial sugar high.

4 - Reduce stress. Studies in animals have shown that exposure to chronic stress increases circulating ghrelin and growth hormone levels (Massachusettes Institute of Technology, 2013). It also interacts with the brain’s reward pathways to increase food intake, creating a vicious cycle where we begin to see food as a comfort during times of stress and anxiety. Incorporate yoga, meditation or breathing into your daily routine, get out for a walk or run in nature, find something that works for you to allow you to live (and eat) more mindfully.

5 - Sleep well. Sleep deprivation has been associated with an increase in ghrelin levels, appetite and hunger comparative to sleeping for longer periods. Aim for 7-9 hours per night, practice good sleep hygiene by limiting screen time, avoiding heavy meals and alcohol before bed, and try to stick to regular sleep and waking up times to regulate the circadian rhythm.

6 - Exercise. Research in recent years has indicated a link between High Intensity Interval Training (HIIT), reduced ghrelin and increased leptin levels. Incorporate some high intensity exercise to your lifestyle each week – circuits, sprints, cycling. Get out and get a sweat on!

If you’re looking for support with weight loss or indeed weight gain, incorporating these diet and lifestyle changes would be a great place to start. It’s important to remember however, that ghrelin is only one of many interrelated factors, which could be impacting on your health and wellbeing.

References:

Massachusetts Institute of Technology.

"Ghrelin, a stress-induced hormone, primes the brain for PTSD."

ScienceDaily - 15 October 2013.