May 23, 2009 • By Stephen Smith •
Copyright (c) 2009 Stephen Smith
Insulin, leptin and ghrelin are three hormones that have a massive impact on your ability to lose weight and keep it off. By understanding the functions and actions of these 3 hormones in your body you will have a much greater chance of controlling them and therefore accelerating the fat-burning process in your body.
Insulin is produced by the beta cells in the pancreas. It gets produced primarily in response to a rise in blood glucose and to a lesser extent blood amino acids. Insulin is a storage hormone. Its function is to take nutrients from the blood stream and store them in body cells.
Insulin has the ability to increase the uptake of glucose into the liver and muscles for storage as glycogen (storage carbohydrate); it can also increase the uptake of glucose by fat cells where it can then be stored as body fat; it also increases the uptake of amino acids into muscle tissue where it can be used to build muscle.
Since insulin is a storage hormone (rather than a mobilising hormone), it also stops the body from mobilising and utilising fat as a fuel source; it stops fat burning immediately!
Therefore, if your goal is to burn off body fat as quickly as possible, your goal should be to keep insulin as low as possible. By doing so your body will then be able to access as burn fat all day long.
So, how do you do that? There are several ways you can keep insulin low:
-Have many small meals throughout the day rather than fewer large meals. Larger meals tend to cause a greater insulin response.
-Control your carbohydrate intake. A greater amount of carbs in a meal induces a greater insulin response.
-Emphasise more low-density carbs and less high-density carbs. The low-density carbs (broccoli, cauliflower, green beens, carrots, etc.) have more fibre and less carbohydrate in them whereas the high-density carbs (bread, pasta, rice, cereals, etc.) have more carbohydrate and less fibre.
-Take a glucose disposal agent with lunch and dinner. glucose disposal agents are specific nutrients that increase the uptake of glucose and amino acids into lean tissue cells, not fat cells. They also assist insulin in its function by acting as co-factors, which means less insulin is required to perform its function.
Leptin is a hormone produced by the fat cells. It is present in the blood stream and its level is in direct proportion to the amount of body fat a person has. i.e. the more fat, the more leptin is produced.
Leptin's primary function is to act on the hypothalamus, the part of the brain that controls appetite and satiety. It tells the hypothalamus to reduce appetite (because fat stores are high), which results in decreased food intake.
On the other hand, when fat stores are low, for example, after dieting, leptin levels are reduced. This causes the hypothalamus to increase appetite. An increased appetite obviously results in greater food intake and a corresponding increase in body fat stores. More body fat results in more leptin being produced, which then tells the hypothalamus to decrease appetite, leading to a reduced food intake. This is a classic negative feedback mechanism.
Leptin may be one of the main hormones responsible for rebound weight gain after a diet.
Leptin is accurately described as an anti-starvation hormone because low levels lead to increased hunger. In the past it was described as an anti-obesity hormone but researchers have since discovered that obese people (who produce large amounts of leptin) are resistant to its action. This is in a similar way that some people are resistant to insulin.
It is possible that leptin resistance may result from over-eating. When someone over-eats as a result of emotional eating or a conditioned response (a habit that has been created), the receptors in the hypothalamus become de-sensitised to the action of leptin. This means that the hypothalamus can't detect when leptin levels are high, resulting in food cravings and further weight gain. Over time obesity results.
It is also theorised that leptin may have trouble crossing the blood-brain barrier in obese people, which means it can't then stimulate the receptors in the hypothalamus. Leptin's reduced ability to cross the blood-brain barrier is thought to be due to the fact that obese people have a cerebrospinal fluid (CSF) to plasma ratio much lower than non-obese individuals.
It is also possible that poor sleeping habits may exacerbate leptin resistance because the sleep hormone, melatonin, appears to have a close relationship with leptin.
Interestingly, many overweight individuals suffer from sleep apnea, a sleep disorder caused by the epiglottis closing over the airways during sleep. Since this may cause them to wake up regularly during the night, melatonin production may become impaired, which then impacts on leptin as well.
With regards to leptin, we should aim to increase its production as much as possible without gaining fat and also try and make the hypothalamus as sensitive as possible to it.
One of the best ways to increase leptin production without gaining body fat is to have a Treat Day once a week. This will be particularly beneficial in preventing the common rebound weight gain that follows a diet.
On the Treat Day people should only have 1 or 2 meals where they eat anything they want and as much as they want (it doesn't mean you can eat anything you want all day long!). This increased calorie intake will prompt the adipocytes (fat cells) to produce more leptin, which then tells the hypothalamus to reduce your appetite.
In order to prevent or overcome leptin resistance the following strategies should be employed:
- Avoid excess sugar and bad fats.
- Perform regular, daily exercise.
- Improve sleeping habits.
- Use the following supplements: melatonin, L-carnitine, CLA and omega-3 fatty acids.
Ghrelin is a hormone secreted by the stomach. Like leptin, it acts on the hypothalamus but in the case ghrelin it increases appetite rather than decreases it (as leptin does).
The levels of ghrelin appear to be regulated throughout the day and are closely correlated with meal time (levels of ghrelin are highest just before a meal).
In fact, in one study, when people were given ghrelin injections and then offered a buffet meal, they ate 30% more than they normally would!
It is believed that one of the main reasons why people tend to put lost weight back on after a diet is because ghrelin levels increase dramatically after a diet. This results in uncontrollable hunger and eventually over-eating by the dieter.
Perhaps if there was some way to blunt the effects of ghrelin we could reduce appetite and therefore keep the weight off. Well, there is! It is a hormone called, Peptide YY3-36. It is also produced by the stomach cells and has the effect of reducing ghrelin secretion.
Lean people tend to produce more of this hormone than obese people, which adds weight to the fact that obesity is more of a metabolic disorder than was first thought. Nevertheless, it is possible to increase the body's production of Peptide YY3-36 and that is by having small, frequent meals.
By doing so, the stomach has small amounts of food in it throughout the day, which then stimulates secretion of Peptide YY3-36 and which in turn, reduces ghrelin secretion and keeps hunger reduced.
Now that you have a better understanding of how these hormones influence our body's storage of fat as well as our ability to lose weight and keep it off, you can easily modify your lifestyle to ensure that it is conducive to helping you achieve and maintain a lean body.