There are many factors at play when it comes to appetite control, food cravings and the sensations of feeling hungry or satiated.
Aside from the more obvious mental-emotional connection to food, emotional eating, food addiction and poor dietary habits that stimulate poor food choice, there are a few key factors that control our desire to eat and feel a sense of fullness. Hormones. Our hunger and sense of satiety are controlled by a handful of hormones that send signals to our brain, telling us that we are full, or that it’s time to eat. The problem here is that these hormones, just like every other hormone in the body, can often stop functioning the way they should. Often, in the face of excess weight gain and obesity, there is a disconnect in the regulation of these important chemicals. The two key hormones that control our desire to eat are leptin and ghrelin, as well as a few lesser-known peptides that are produced in the stomach.
The gastrointestinal tract has more functions than you might think, and I’m sure you’ve heard before that “everything stems from the gut”. This statement isn’t entirely inaccurate. The gut is the largest endocrine (hormone) organ in the body, with the gut hormones working on more than just digestion and nutrient absorption. They have also been shown to influence energy intake and play a role in satiety and food consumption. The mechanism by which they exercise this hormonal role continues to be studied extensively. They act as true hormones, exerting their effects on distant organs and interacting with the brain and the centers of appetite control. This explains how the gut tells us that we’re full or that we need to eat.
Leptin and ghrelin are the two major players here.
Ghrelin: The hormone that says, “I’m hungry!”
Ghrelin is a hormone produced by cells in the stomach and in the pancreas that stimulates hunger, telling our brain that it’s time to eat. Ghrelin levels increase before a meal and decrease afterwards – a normal response. Ghrelin increases our food intake, as well as fat mass, by activating cells that are also leptin- and insulin-sensitive. It also stimulates growth hormone production and plays a role in our pleasure-reward centers, which may contribute to emotional eating.
Leptin: The hormone that says, “I’m full!”
Leptin is the counterpart of ghrelin. It is a powerful and influential hormone produced by our adipose (fat) cells and tells us that we’re full, allowing us to feel satiated, as the levels increase – telling us to STOP eating (another reason to eat slowly, so that this hormone has time to make it to the brain). Otherwise, you’ll end up overeating by the time your brain realizes you’re full. Leptin is what allows your fat cells to communicate with your brain, letting it know how much energy you have available and what to do with it. This makes it a very important hormone with respect to our metabolism. When leptin signals work properly, when fat stores are full, leptin levels will increase, which then tells your brain that you’re full and to stop eating.
Essentially, when it comes to weight loss, you would think that more leptin is better. There was a lot of research being done looking into leptin injections in overweight and obese individuals in order to control weight loss. You would assume that obese individuals would have lower leptin levels and that leptin injections would cause weight loss. However, only 5 to 10% of obese individuals seem to respond to this. Interestingly, when fat mass increases, so does leptin, and yet these individuals didn’t have a decreased sense of hunger. Obesity and weight gain seem to throw off these two hormones. Sound complicated? That’s because it is.
Leptin Resistance
Generally, obese individuals have unusually high levels of leptin – translation: they become resistant! The same way that diabetics become resistant to insulin. The continually high levels of and over-exposure to leptin that is being made from the fat cells desensitizes these people, so the body doesn’t receive the adequate “I’m full” signal that it should. You don’t get a drop in appetite or an increase in metabolism, as leptin is supposed to cause. The brain might even think you’re starving and you get even hungrier.
It’s a continual cycle:
Eat – gain weight – increase fat cells – more leptin – leptin signalling problems – brain thinks you’re starving – eat more – gain more weight – get even hungrier…
A few leptin fun facts:
- Interestingly, insulin and leptin resistance seem to occur together in obese individuals, with men having more abdominal fat and more insulin and women having more fat under the skin and higher leptin levels.
- Dieting (FAD diets and yo-yo dieting) causes changes in leptin and ghrelin, which contribute to increased hunger and weight regain after the diet. These changes can persist for MONTHS after your “diet” has ended. An excellent explanation as to why you gain all the weight back and more.
- A weight loss of 5% of your body weight or more contributes to a large drop in insulin and leptin and higher ghrelin levels versus someone who loses less than 5%.
- Hormones, such as growth hormone and estrogen, impact our hunger hormones.
- Leptin seems to play a role in reproduction and fertility in women, which is related to a woman’s body fat levels.
- Estrogen levels in women and testosterone levels in men seem to affect how a person responds to hunger hormones and if they gain or lose weight.
- Women seem to be more sensitive to leptin than men, unless men are given estrogen (perhaps another reason women tend to lose weight at a slower rate than men).
- Some researchers believe that inflammation may lie at the root of leptin resistance. Obesity is an inflammatory state, after all, so this isn’t a surprise.
Confused yet? You should be. It’s a complicated topic and it’s the reason weight loss can be such a struggle for some people. There’s no magic pill, nor is there a prescription that will fix these hunger hormones. It all comes down to lifestyle and diet.
Here are a few tips to manage and re-balance your leptin and ghrelin levels:
- Fish Oils: Omega fatty acids appear to be linked to a decrease in hunger and an improvement in ghrelin and leptin levels. They may also help to fight leptin resistance.
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- Manage Inflammation: If inflammation is at the root of obesity and possibly leptin resistance, following an anti-inflammatory diet is key. Increase your healthy fats, reduce your processed foods and fast foods, eliminate refined sugars, consume low glycemic index carbs and lots of healthy protein, as well as lots of fruits and veggies. All the usual things – but this just gives you another reason to really try and stick with it.
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- Avoid low-calories diets (less than 1,000 kcal/day): These diets disrupt your diet hormones and lead to overeating and weight regain later. Don’t skip meals either, you delay leptin output, so your body keeps releasing ghrelin – meaning you’ll probably binge eat later and you’ll be less likely to make a health choice at that point.
- Increase your protein: Protein helps to manage hunger and may improve leptin sensitivity.Truestar Solution: TrueSTRENGTH
- Keep a healthy gut: The gut can impact our health dramatically. Studies are finding that a healthy gut can control appetite and that gut disorders, such as colitis, appear to be linked to leptin and ghrelin imbalances.
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Weight loss is never easy and re balancing an unbalanced system can be frustrating and take time. Make time to exercise, try implementing goal setting and behavioral changes and make sure you have a great support system to help you along the way.