Fat gain and loss is regulated by a hormone called leptin in a process infinitely more complex than the simple “calories in, calories out” scenario presented as the basic science of energy regulation.
Leptin is the messenger signaling our bodies when it’s time to eat, as well as how much to consume, and the apportioning of resources for energy and fat storage. Leptin resistance is what happens when those messages get skewed. (1)
Obesity researchers now believe leptin resistance and the disruption of this cycle is the main reason why people get fat and find it difficult to lose weight. (2)
Leptin earned its designation as the “master fat hormone” partly because it’s manufactured in the fat cells themselves as an integral step in the process of keeping the brain updated in regard to food intake and energy requirements. (3)
It all boils down to this: either we’re full (satiated), and we have enough fat stored for safety to burn calories at a normal rate; or we’re running on empty (starving) and need to take in more food for current energy needs, and put some away for later. (4)
That makes understanding the “how”s and “why”s of leptin vital to everyone who’s ever struggled with weight control.
Let’s take a closer look at the way leptin works in the body and what you can do to normalize the messaging system if it’s skewed.
The Leptin Feedback Loop
Since leptin is made by fat cells, the more fat cells we have, the more leptin we produce. (7) Released into the bloodstream, leptin is carried to the brain where it communicates the situation to the hypothalamus, the part of the brain that tells us when to eat and how much to eat. (8)
High levels of leptin give the message we have enough fat, and low levels indicate we need more to survive. (9)
This negative feedback loop is much like the control mechanisms for regulating temperature, breathing and blood pressure.
We eat, and body fat increases along with leptin production, kicking us into a pattern where we eat less and burn more; when we eat less, body fat and leptin production decrease, and we burn fewer calories.
At least, that’s the way it supposed to work.
When a person is carrying lots of body fat, there’s a lot of leptin being secreted into the blood stream and sent to the brain. But when the brain doesn’t detect the leptin, the message to stop eating isn’t received. (10)
Leptin resistance is the culprit in obesity, not a lack of self-control. (11)
Here’s what happens when the brain thinks we don’t have enough fat:
- We eat more food to prevent starvation
- We burn less calories to conserve fat stores, even at rest
- We feel lethargic; movement would require precious fuel
Gaining weight isn’t caused by eating more and exercising less; it’s a hormonal deficiency that makes altering the cycle of eating and storing fat nearly impossible to change. (15)
Leptin Resistance Sabotages Weight Loss
When we cut back on fat mass, there is less leptin circulating in the blood, but this doesn’t necessarily correct the leptin resistance issue. New research shows leptin resistance may well be the reason why diet success is so rare, and often temporary. (16, 17)
Lower leptin levels can lead to cravings, hunger, lethargy, and increased appetite, as well as lower metabolism. (18)
After we lose weight, the brain initiates mechanisms to increase and protect fat stores it perceives necessary for survival, triggering “feeding” behavior at odds with what the rational mind wants: to keep off the excess weight we dropped. (19)
- The hypothalamus is bombarded by inflammatory signals
- High levels of free fatty acids levels in the bloodstream jack up fat metabolites and short-circuit the leptin signaling
- Elevated leptin levels appear to lead to more pronounced leptin resistance over time
Since these three biological circumstances are usually more evident in obese people, it can create a situation where more fat accumulates as leptin resistance grows.
How to Reverse Leptin Resistance
If you have a lot of belly fat, you most likely have a leptin resistance problem. Reducing inflammation through dietary choices is a solid strategy for beginning the process of correcting the signaling issue that caused you to gain the fat in the first place.
Start with these methods for decreasing leptin resistance:
- Eating plenty of protein leads to weight loss and may increase leptin sensitivity (22)
- Lower blood triglycerides through cutting back on carbohydrates (23); elevated levels of blood triglycerides can prevent leptin from reaching the brain (24)
- Get plenty of shut-eye; poor sleep may contribute to leptin signaling problems (25)
- Exercise even if you don’t feel like it; moving your body can help reverse resistance (26)
- Eating foods rich in soluble fiber to condition the gut may help protect against weight gain (27)
- Avoid processed foods, which impair gut health and may contribute to inflammation (28)
Since these choices are all associated with creating good overall health, it’s clear that normalizing the function of this vital hormone requires a shift in lifestyle.
The Bottom Line
The Western diet has proven its ability to negatively impact health worldwide. Once a culture adopts this way of eating, populations begin to suffer from chronic diseases like diabetes, obesity and heart disease within a few years.
In 2012, 69% of Americans were either overweight or obese, and the numbers get higher every year. (29) The incidence of chronic disease continues to grow, fueling the current health crisis.
If you’re one of the majority when it comes to carrying excess weight, stop blaming yourself for being lazy and fat, for regaining weight you lost and adding more; get real about the biological factors causing the vicious cycle and take action to fix the problem.
Summary: Body fat is regulated by leptin, the “master fat hormone.” Take the necessary steps to begin correcting leptin resistance, and you may yet win the war on fat.