Over the last few years, I’ve come across a number of references to a hormone called Leptin that have piqued my interest. So, I decided to do a bit of research to find out more about it… Hormones are the great communicators of our bodies. They deliver information from a single cell, or a group of cells, to another cell or another group of cells. Some hormones, released by endocrine glands, travel via the bloodstream; others, released by exocrine glands, travel via ducts to their target cells.
While the layperson readily associates endocrine hormones with major glands like the pituitary, adrenal, thyroid, adrenal, pancreas, ovaries and testes, amongst others, there are numerous glands in various tissues throughout the body that secrete hormones.
Leptin, which was only discovered in 1994, is a hormone that is mostly, but not exclusively, produced in fat tissue. It is what is called a ‘peptide hormone’. Peptides are short chains of amino acids, the basic building blocks of proteins. Proteins, otherwise known as ‘polypeptides’ are long chains of amino acids.
Peptide hormones are synthesized via a metabolic process that begins with the DNA and RNA inside the nucleus of a cell, and ends up at the cell membrane ready to be secreted as a reaction to some specific stimulation. They travel to the target cells, where they interact at specific receptor sites on the cell membrane.
It is known from animal studies that Leptin (“Leptos” means “thin” in Greek) plays a significant role in the control of food intake and body weight regulation. Injection of Leptin into the brain or bloodstream of rodents resulted in lower food intake and body weight, and the greater the amount injected, the greater the effect.
Receptor sites where leptin attaches are found in many tissues in the body, including the brain. This apparently supports an idea, known as the ‘lipostatic theory”, that has been around for nearly fifty years. In short, this suggested that there was a feedback loop by which some at the time unknown product of fat metabolism is released into the bloodstream and acts as a signal to the hypothalamus – the gland that controls appetite, and body temperature, amongst other things – to feel satiated and cause it to stop eating. In addition, Leptin also signals the body to burn off excess fat. So, it plays a double role in maintaining appropriate body weight.
While researchers didn’t know what the substance was, they surmised that the theory was correct based on an experiment that joined the circulatory systems of two rats, one with a damaged hypothalamus, the other normal. The former had no sense of satiety, overate and grew obese. The latter grew abnormally thin. Presumably this was because the fat tissues of the ‘hypothalamically challenged’ rat was producing a ‘satiety factor’ which it could not detect, but which stimulated the normal rat to lose its appetite.
It has been found that the amount of leptin produced in the body is proportional to body fat. And, more obese a person (or animal) is, the greater the amount of leptin produced by each fat cell. It is logical to assume that this rise in leptin should act to reduce the amount of food eaten by an obese person. But that doesn’t seem to be the case. Instead, these individuals seem to develop an insensitivity or resistance to the message that the leptin is trying to deliver. Effectively, they are like the rat with the damaged hypothalamus.
There is an interesting parallel here with people who suffer from type 2 (otherwise known as ‘adult onset’) diabetes. While type 1 diabetes, known as ‘childhood diabetes’, is characterized by the marked decrease or total absence of insulin, type 2 comes about as the result of a decrease in cellular sensitivity to insulin. As in the case of leptin, insulin is present but the cells no longer respond to it, they are ‘insulin resistant’.
The relationship between leptin and insulin appears to run deeper than the fact that they are both hormones to which the body can become resistant. In fact, according to Dr. Ron Rosedale, who has researched and written extensively on the roles of both leptin and insulin, control of these two hormones is the most crucial element in curing many of the most prevalent chronic illnesses that plague modern societies. Insulin and leptin control, that is the reduction of the amount in the body, is essential in healing illnesses such as heart disease, diabetes and obesity.
Leptin levels can be measured by a blood test and it seems that most overweight people, especially the obese, are putting on weight not because they have insufficient leptin, but because they are resistant to it. The more resistant a person becomes, the more he or she will eat in order to feel satisfied and the more it will store up fat. As the fat cells increase the production of leptin in an attempt to communicate with the body to stop eating and storing fat, the greater the resistance will become. Thus a vicious cycle is established which aggravates the overeating, the obesity and the leptin resistance.
The question becomes how to break this cycle. The answer to this is the basis of a number of books that address leptin imbalance and propose similar therapeutic dietary recommendations. In addition to Dr. Rosedale’s “The Rosedale Diet”, there is “The Fat Resistant Diet, written by the veteran nutritional physician Leo Galland as well as Byron Richards’s “Mastering Leptin”.
References: 1. “Leptin: Your brain, appetite and obesity”, David Sunter, Donal O'Shea & Stephen R Bloom; Endocrine Unit, Imperial College School of Medicine Hammersmith Hospital, London
2. Leptin: A Piece of the Obesity Pie, Minh Liu; August 2004; The Science Creative Quarterly, Issue 2.
PART II
This diet and that diet… Most of us are suffering from ‘diet fatigue’ – especially when we hear of yet another new one. But the fact is that almost all of us benefit from consciously choosing the type and amount of we eat. Most of these diets do work for some people and all of them don’t work for everyone. The trick is to match the right diet to the right person.
How that is done is a question for another day. But let’s talk a bit about another type of diet, the leptin diet, or perhaps more accurately, ‘the leptin control diet’. As you might recall from the previous column, leptin is a relatively recently discovered hormone, produced in fat tissue, that is released into the blood stream travels to the brain where it stimulates a sense of satiety as well as signaling the body to burn excess fat.
With this leptin feedback loop in place, it is reasonable to wonder why is it that there are so many overweight and obese people. Research shows that the more body fat and the more weight put on, the greater the amount of leptin produced by the fat cells. What has gone wrong that prevents people from being satiated and why are their bodies not burning off the excess fat?
The answer, according to a number of authorities on leptin, is that there is a widespread problem with ‘leptin resistance’. That is, the fat cells are producing sufficient amounts of leptin, but the body is no longer responding to it. This is similar to type 2 diabetes, the adult onset variety of the disease, otherwise known as ‘insulin resistant diabetes’. The pancreas still has the capacity to manufacture insulin, but the cells no longer respond to it.
There are a number of similarities between insulin resistance and leptin resistance. While it might be said that a genetic disposition toward diabetes exists, in the end, insulin resistance is the result of an excessive production of insulin due to excessive intake of carbohydrates, usually in the form of grains, sugars and other high glycemic foods (that is, foods that break down into sugars rapidly).
Really, the genetic disposition is toward a way of eating – not toward a disease. Too much insulin and too many swings in insulin levels causes the cells to lose their capacity to ‘hear’ insulin’s message. It can be thought of as a type of metabolic fatigue, or what some have characterized as a communications breakdown.
Likewise, eating habits that stimulate a long term excessive production of leptins will result in a breakdown in the feedback loop to the brain. Leptins will no longer be able to communicate their message, dietary satiation will be lost and surplus fat tissue will not be burned off.
In the both the case of insulin and leptin, the way to reverse the vicious cycle is to redevelop a sensitivity to the hormone by appropriate dietary intake. The basic principle of insulin control which is the common thread found in any number of low carbohydrate diets is to drastically reduce or eliminate starchy carbs: grains, sugars and other high glycemic foods.
According to several sources listed below, the basic principles for becoming resensitized to leptins are:
1. Fast for the 11 or 12 hours between supper and breakfast and allow 3 hours between the end of supper and going to sleep.
The reason for this is that the body is burning calories from the evening meal for the first 6 to 8 hours after eating it. The best time for burning excessive fat occurs after that, approximately 8 to 12 hours after eating. Late meals or snacks will give the signal that there is no need to burn fat at night.
2. Back to 3 squares meals per day with 5-6 hours between them and no snacking. Snacking stimulate release of insulin. When insulin is being released, the body does not burn off fat. It is suggested that if this schedule of 3 meals without snacks is hard to follow, if there are drops in blood sugar in the intervals between meals, then begin with 4 meals daily and an increase in daily exercise. Over time, one can switch to a 3 meal a day schedule.
3. Don’t overeat. More food than is needed is the basic cause of leptin (and insulin) resistance. Return to the old standbys of eating slowly and chewing well. Relax, enjoy the experience and the taste.
4. High-protein breakfast in the morning. This will prevent energy dips in the afternoon. Too many carbs with inadequate protein will cause the blood sugar to dip, resulting in that all too familiar struggle to keep one’s eyes open later on in the day. Leptin resistant people who take in too many carbs early in the day tend to overeat.
5. In general, eat fewer carbohydrates and eat low glycemic ones. This does not mean no or even very low carbs, but the amount of starchy carbs should be balanced by a similar quantity of protein. Carbohydrates from fibrous vegetables are encouraged.
While the majority of diets can be categorized as high carbohydrate/low fat or high protein/low carbohydrate, the leptin sensitizing diet really does not fall into the either category. Instead, the focus is on balance, appropriate intake of fats and providing the body an opportunity to burn off fat.
While there is no one single way of eating that works for everyone, this type of diet seems to hit the mark for many people with weight problems.
*To learn more about a leptin control diet, the following books are useful: “ Mastering Leptin” by Byron Richards “The Fat Resistant Diet” by Leo Galland “The Rosedale Diet”, by Dr. Ron Rosedale