The role of Leptin & Grehlin in losing fat and improving your health.

shutterstock 311180945 1Leptin and Ghrelin are two opposing hormones that along with insulin effects the way our brain controls fat metabolism. Following a calorie restrictive diet these two hormones are mainly responsible for fat going back to pre-diet levels. Note: If leptin is low ghrelin will be high.


Ghrelin is known as the hunger hormone and is a peptide that triggers the part of your brain called the hypothalamus to make you feel hungry, which means you will eat more. As blood sugar levels fall, ghrelin levels will rise. As well as increasing appetite it also stimulates Growth Hormone which in turn ramps up your metabolism.

Ghrelin is synthesized predominantly in the stomach and is found in the circulatory system of healthy humans. So ghrelin promotes weight gain and fat accumulation.

Obesity and fat accumulation are a modern epidemic, and in order to understand the physiology of obesity it is necessary to have an understanding of how these hormones effect body homeostasis or keeping the body in balance.

This is the problem with low calorie diets, by only concentrating on reducing your calories or increasing your energy expenditure you’re missing the real reason of why you are fat and what is keeping you fat.

Your hormones and metabolism will adjust to re-gaining the weight you have lost and usually add more. Ghrelin levels increase significantly on a weight loss diet, and the longer the diet, the more your levels will increase.

Note: If you are eating a normal glucose/carbohydrate diet (which most people do), you need to eat smaller meals more often, so blood sugar levels (BSL) don't go too low. If they are low, ghrelin will be high, and the higher they go the hungrier you will be. So eat smaller meals often so BSLs don't go too low.

Note: Ghrelin is high before you eat and low after you eat. At night you want Ghrelin to be high, because when it is high, fat is being burned, but resist the urge to eat because you will switch off fat burn.

Ghrelin’s ability to switch the body over from fat burning to glucose burning is OK if you are lean but no good if you are trying to lose fat. Insulin has a similar property in the way that when insulin levels are high fat will be stored and not burned for energy. So if you are in a normal glucose burning mode, (which most people are) eat every 3 hours and eat low glycemic carbohydrates.

Note: If you are eating a ketogenic diet you don’t have these problems.


The other hormone Leptin, was discovered more than a decade ago and is a regulatory hormone produced by our fat cells and controls how energy is consumed and used in the body. It tells your brain how much energy is available and what to do with it.

Increased leptin levels is a marker of leptin resistance and is seen in the obese and independently associated with insulin resistance and cardiovascular disease (CVD) in humans.

When you lose fat, leptin levels drop. If blood sugar levels are too low, your brain thinks you are in starvation mode and the vagus nerve is stimulated, causing excess calories to be stored as fat. This will not happen if you are in ketosis and burning fat rather than glucose.

Reducing food intake decreases leptin levels, but if you reduce calories too much that will lead to acute hunger and quite possibly higher fat levels. This will happen due to eating too much of the wrong food when you are hungry.

Leptin production is primarily regulated by insulin-induced changes in fat metabolism. The more fat you have (in general) the more leptin you will secrete. The problem is, the fatter you are the more likely you will have leptin resistance. The signal to stop eating and ramp up energy levels won’t happen because the leptin message isn’t getting through.

Here is how it works - in a normal healthy person after they eat:

Leptin levels increase, which signals the hypothalamus in the control center of the brain to lower levels of a neurotransmitter called neuropeptide Y (NPY). This in turn lowers the desire to eat and lowers fat deposition, but as mentioned above, if the leptin signaling process is damaged, the signal will not reach the control center of the brain, and you will not feel full and will keep on eating.

Leptin resistance (LR).

LR happens because too much leptin is circulating in the body and mainly occurs in people who are over weight or obese. If they are, there's a good chance they will have LR. LR is the brain’s inability to detect satiety, so you will keep feeling hungry, despite having high energy reserves and fat stores. Energy intake and body weight are tightly regulated by these control systems.

Note: Leptin is the way your fat cells tell your brain that your energy thermostat is set right. It is the master regulator of appetite. Unfortunately for us leptin is more sensitive to starvation than overeating, so its primary role is to top up fat cells than to decrease fat levels, which is why you need to control it.

Signs you may have Leptin Resistance

  • Inflammation including high levels of C-reactive protein' (CRP) (High CRP is linked to CVD) (blood tests can detect this)
  • Increase in circulating leptin
  • High blood triglycerides
  • High blood glucose
  • High blood insulin
  • Insulin resistance (insulin resistance is closely related to leptin resistance)
  • Low thyroid hormone T3
  • Leaky gut (toxins leaking through the gut wall into blood vessels)

OK so what does all this mean? I’m going to write down in point form a very simple summary of what you need to remember.

  1. Both Ghrelin and Leptin work together to suppress the fattening effects of Insulin. You need all 3 to be in sync.
  2. At night if you feel hungry don’t eat, because fat burn will stop and fat storage will start.
  3. Leptin makes you feel full, Ghrelin makes you feel hungry.
  4. If both Leptin and Ghrelin are not working properly because of insulin and leptin resistance you will overeat and get fat.
  5. To keep all of these hormones working properly you need to lower insulin resistance, and you do this by eating natural, healthy, high fiber meals and lowering the carbohydrates. (the amount will depend on how insulin and leptin resistant you are).
  6. Replace carbohydrates with good fat. (see previous posts)
  7. If you are not on a ketogenic diet, eat every 3 hours and keep the carbs ‘low glycemic’.
  8. If you are insulin resistant (see a good health care professional to find out) you most likely will be leptin resistant. The older and fatter you are the harder it is to reverse these problems, but you can get amazing results. Remember lower carbs and raise fats (saturated and mono unsaturated, not polyunsaturated omega 6 oils)
  9. Remember this! Your body has evolved to store fat as a survival mechanism. You have to learn to manipulate the way you eat so your body releases fat and stops storing it.
  10. Fat is released by manipulating hormones not by eating less and exercising more.
  11. Exercise helps weight loss by increasing insulin and leptin sensitivity, not so much by burning calories. (to burn the caloriesMfrom a couple of doughnuts you have to exercise for about a hour, easier not to eat the doughnuts!)
  12. Get yourself someone who understands all this and will guide you through a sensible eating plan – one that works for the long term, not just for 12 months.

Note: Last but not least, leptin regulates components of your immune system ie those cells that fight disease, but if you have metabolic disfunction and your leptin levels are out of wack, it will impair your immune system’s function and leave you susceptible to illness and disease.

I hope you find this helpful. All this information includes the latest scientific research available today. I believe it is just a matter of time before government health agencies start to adopt many of these principals, because the health guidelines they have been using do not work. Obesity, Type 11 diabetes and many other diseases are out of control, and that should tell you something. Instead of going to the doctor for a pill, start taking control of your health and look carefully at what you eat, it’s your body.