Category Archives: Triglycerides

Leptin Resistance

What is Leptin?

Leptin is a hormone released by fat cells that helps regulate hunger. And it may hold the key to why a low carb / paleo diet works for so many people.

Role of Leptin in Hunger Signals
Leptin and Hunger
(Click Image to Enlarge)

Success on a low carb / paleo diet is often attributed to “never feeling hungry”, an effect not seen on other diets. People point to the satiating aspects of fat or protein in eliminating hunger, but dieters may be suffering from a rarely diagnosed condition called leptin resistance that is corrected by the low carb diet.

Leptin circulates through the bloodstream in an amount directly proportional to the amount of fat you have. In theory, the more leptin you have circulating the less you will eat, because it signals that you have enough stored energy for all your metabolic processes. When leptin levels dip, it signals the brain that you are hungry.

So, that means fat people should never be hungry, right? Not so fast, grasshopper.

Resistance is Futile

Most low carbers are familiar with the concept of insulin resistance in those with type two diabetes and metabolic syndrome. In a healthy individual, insulin signals the cells that glucose is available, and the cells respond and allow the glucose to enter the cell (if they need the energy). Insulin resistance is a condition where the cells become resistant to the effects of insulin, requiring more and more insulin to deal with blood sugar levels. If a regular cell opens the door to a gentle knock, the insulin resistant cells respond only to ferocious pounding on the door with a battering-ram’s worth of insulin. The pancreas, which produces insulin, cannot keep up with the demand for more and more insulin, and dangerously high levels of blood glucose result.

A similar thing happens with leptin resistance, but through a different mechanism. There’s no shortage of leptin in an otherwise healthy obese person, and the fat cells never grow tired of producing it. But the circulating leptin is blocked and cannot turn off the hunger signal. The fat person remains hungry. And hungry people eat.

What Causes Leptin Resistance?

Some have theorized that dietary fat and blood glucose levels interfere with leptin. While there is a link between leptin resistance and the levels of fat circulating in the blood (triglycerides), eating dietary fat doesn’t seem to have an effect. Recent evidence showing a diet high in fructose contributes to leptin resistance adds to the growing body of evidence against high levels of fructose in the diet. The amount of fat in the diet did not matter; leptin resistance peaked with the high fructose diet, and reversed itself to normal levels when the rats ate a sugar free diet, no matter how much fat they had. Lucky rats.

We know that leptin signals our brain that enough energy is present, and the body does not need any more food. Leptin is able to cross the “blood brain barrier” (BBB) to do this. The BBB is a protective system of small capillaries that protects the brain from most chemicals but allows the important ones through. It works like a filter. So what causes the curious case of leptin resistance, where this essential hormone is blocked by the BBB? As Dr. Mike Eades explains:

Research done a couple of years ago in St. Louis and in Japan pinpointed the problem. Triglycerides – fat circulating in the blood – interrupts the passage of leptin across the BBB. If trigylcerides are high, which they are in most obese people, then, basically, they block the movement of leptin into the brain. So, leptin levels are elevated in the blood, and triglycerides keep the leptin from getting to where it needs to get to shut off hunger.

One Solution

Controlling trigylceride levels can reverse leptin resistance. In my own experience, hunger evaporated on my low carb diet as my triglycerides fell from 344 to 105. Before that, I was often hungry, even after eating past the feeling of fullness and often to discomfort. On my low fat diet 15 years before, I was miserable because I was always hungry. But that, as they say, is a personal testimony and not a scientific finding. Too bad I’m not a rat.

The easiest way for most people to lower triglyceride levels is to adopt a very low carb diet (less than 50 grams of carbohydrate per day), then transition to a moderate carb diet devoid of most grains. Niacin and fish oil have also proven to be effective in many people, even those with genetic reasons for high triglycerides (familial hypertriglyceridemia). I combine all three approaches, and have found the eliminating any one of those results in my triglycerides rising again. Management of triglycerides in this way is done in concert with a physician and blood tests. Those with chronic health problems should check with their doctors first, of course, especially those with reduced liver or kidney function, or those suffering from conditions such as gout that require specific diets.

Resisting Resistance

Humans are adapted to eat a certain diet, and in terms of adaptation, the modern agricultural era is a blip on the radar screen. We simply haven’t had time to adapt to large quantities of grain and other carbohydrates in our diets. The inexpensive access to readily available carbohydrates is new, barely 10,000 years old, and our biological machinery is not able to handle it. That’s the philosophical framework under girding the modern low carb / paleo diet movement. The rise of leptin resistance is just one more metabolic condition that supports the effectiveness of a low carb / paleo lifestyle.

Other Resources

MegaSearch: Leptin Resistance

Heart Scan Blog: Niacin

Heart Scan Blog: Fish Oil

Another Study: Low Fat / High Carb Dangerous

At Low Carb Age, we’re chronicling the end of the low fat / high carb age entered in the early 1970s when Congress (yes, Congress) decided that reducing saturated fat was the best way to improve American health. Yet another crack in the edifice comes from a new study by the University of Glasgow published in the Annals of Nutrition and Metabolism:

Conclusion: In postmenopausal women, following the UK dietary guidelines resulted in changes in the lipid profile that were more likely to favour an increased risk of CHD [coronary heart disease], as TAG [triacylglycerol] concentrations were increased and HDL cholesterol concentrations were reduced. However, in addition, we found a significant reduction in BMI and a significant increase in the ‘antioxidant power’ of plasma, which should benefit health.

Studies don’t venture far from the primary aim of the study, as the scientists don’t like to inject opinions into the research. What the authors of the study didn’t say is the people following a low carb, adequate protein diet including plenty of “good fat” also enjoy a significant reduction in BMI (body mass index). And unlike the diet from the dietary guidelines since the 1970s, a low carb diet lowers triglycerides and raises the good cholesterol, HDL.

This study focused on post-menopausal women in Great Britain. Twelve women participated, and started by chronicling their food intake for a week and taking baseline blood tests. Based on their current diet, the authors recommended the women increase their carbohydrate intake to match the official government dietary guidelines. The women were in a “free living” condition, meaning that they were free to live their normal lives at home, at work, etc., and were not confined to a hospital during the study. Blood tests were taken after a week, and then after 4 weeks.

The dietary guidelines in Great Britain are basically the same as in the US. The guidelines specify that a reduction in dietary fat is important, and half the daily “energy intake” is to be from carbohydrates. (In Europe, “calories” are referred to as “energy”, so this equates to the American guideline to obtain about half your caloric intake with carbs).

After a week on the diet with increased carbs, the women were directed to increase their fruit and vegetable intake. For the final three weeks of the study, they were eating the “balanced diet” so familiar to anyone who has seen the “food pyramid” chart.

The good news was that the women lost weight, a result usually seen in the adoption of a low carb diet as well. They also had an increased level of antioxidants in the blood (although not stated, this was probably from the fruit and vegetables they were now eating). But the bad news?

The bad news was that the women experienced a significant rise in triglyceride levels, and a lowering of the protective, good cholesterol HDL. In other words, in 4 short weeks they became like everyone else who tries to follow the official dietary guidelines: candidates for cardiovascular heart disease (CHD). And post-menopausal women are more likely to develop CHD with elevated triglyceride levels.

They were probably healthier before the study started. Even with a BMI much higher; mortality studies show that it is better to have an “overweight” than “healthy” BMI. Even an “obese” BMI puts you at parity with the so-called “healthy” BMI.

LDL – Measure it Directly

My medical history includes a high triglyceride level over 400, and my doctor asked for a direct measurement of my LDL. Usually, the labs calculate the LDL by using a formula rather than measuring it directly. As Dr. Michael Eades says in his blog:

… Friedewald substituted triglycerides (TGL) divided by 5 for VLDL in the above equations, giving us the so-called Friedewald equation for calculating LDL.

LDL = Total cholesterol – HDL – TGL/5

And this is how it is still done in labs all over the world 27 years after Friedewald’s paper. If you’ve had a lab report showing an LDL figure, I can guarantee it was calculated by the Freidewald equation and not measured directly.

It has long been recognized that if the triglycerides are over 400, the calculation does not work. So you have to measure the level directly. In that same blog post, Dr. Eades explains his experience that LDL calculations are inaccurate when the triglycerides are low as well. I have linked two articles Dr. Eades identifies as supporting that position in our new LDL Research Page.

Many studies show marked improvement in patients HDL, triglycerides and glucose levels with low carb diets. Often, the low carb dieter has a rise in total cholesterol and LDL. Researchers are not concerned with the higher total cholesterol number, but the LDL level increase does concern them. But most studies use the Friedewald calculation that may not give an accurate picture of the true LDL level.

If my LDL gets too high, I’ll be certain to ask for a direct measurement of it, rather than a calculation. The extra cost for the test is probably cheaper than taking statins.