1 Reason Why You're Still Fat
The trend in the health, nutrition, and fitness industry over the last decade has always identified “calories in vs calories expended” as what keeps your weight in check. For years research has falsely identified nutrition, exercise, and genetics as the sole factor determining why you are overweight.
Despite extreme dieting, large caloric deficits, and intensive exercise routines; overweight people can’t seem to keep the weight off and new research indicates it could be a physiological response that has to do with a hormone called leptin.
Leptin- The Fat Hormone
Leptin, a hormone that plays a key role in regulating energy intake and energy expenditure, may be one of the most important hormones in your body that will determine your health and lifespan.
Leptin is a very powerful hormone produced by white adipose tissue (fat cells) and sends a signal to receptors on the hypothalamus in the brain. The hypothalamus controls hunger and thirst as well as other functions such as sleep, moods, and body temperature. It also regulates the release of many hormones that have functions throughout the body.(1)
Leptin signals regulate food consumption, energy expenditure, and metabolism. In short, leptin is the way that your fat stores speak to your brain to let your brain know how much energy is available and, very importantly, what to do with it.
How leptin should work
How Leptin Should Work
Leptin Resistance
The way leptin should work is- the more fat that an individual stores, then the more leptin is produced by fat cells, signaling the hypothalamus to stop eating and start burning more of its energy reserves.(2)
However, the problem is that the leptin signal in the brain of obese individuals starts to fail. There’s an abundance of leptin floating around, but the brain doesn’t “see” that it is there. This is known as leptin resistance and is now believed to be the #1 biological factor contributing to human obesity.
You become leptin-resistant by the same general mechanisms that you become insulin-resistant, because their signaling loops are directly correlated. (3)
Having High Leptin: Having elevated levels of leptin due to increased size of adipocytes creates insensitivity much like insulin resistance.
Inflammation: Inflammation in the hypothalamus, due in part to poor nutrition creates damage that is likely an important cause of leptin resistance in both animals and humans.
Free Fatty Acids: Having elevated free fatty acids in the bloodstream may increase fat metabolites in the brain and interfere with leptin signaling.
Effects of Leptin Resistance
Increased Calorie Consumption: The brain believes the individual is in an extreme calorie deficit and signals an increase in hunger as a survival mechanism
Decreased BMR: The brain believes we need to conserve calories to survive so it reduces non-exercise activity thermogenesis which lowers energy expenditure at rest.
Weight Loss Rebound
The majority of weight loss programs do not work, and recent research indicates that once someone becomes obese it is statistically more unlikely they will ever reach a healthy body weight again-and this may be directly linked to leptin.
Losing weight will significantly reduce fat mass, but will also lead to a dramatic decrease in leptin levels, but the brain doesn’t necessarily reverse leptin resistance. This means that the receptors in the hypothalamus are still incapable of binding to leptin efficiently, yet now there is a significantly lowered amount of leptin even being produced.
So despite the body being in a caloric deficit a person’s leptin signaling to maintain a new healthy weight will be distorted leading to a decreased metabolism and increased hunger levels because of the biochemical occurrences at play(4).
Reversing Leptin Resistance
Research around drugs to help improve leptin insensitivity is currently being conducted. Currently science supports improving leptin resistance through lifestyle modification. There are several things you can do to:
Improve Your Gut Health: Avoid simple sugars and highly processed food that will compromise the integrity of your gut bacteria. It is essential that people maintain a balanced ratio of good bacteria throughout their GI tract to promote nutrient absorption, and avoid inflammatory immune responses that could contribute to leptin insensitivity. Consider taking a probiotic if you believe your gut health is compromised.
Exercise: Resistance training and cardiovascular exercise will drive metabolism as well as a create a caloric deficit that will decrease the size of adipocytes.
Lower Your Triglycerides: Having high blood triglycerides can prevent the transport of leptin from blood and into the brain.(5)
Eat Protein: Consumption of a high protein diet will promote weight loss due to the high thermic-effect of protein as well as decrease feelings of hunger associated with leptin insensitivity
