High leptin is tied to obesity, overeating, and inflammation, and if leptin remains high for a long time, leptin resistance may result. Learn about the causes, symptoms & natural factors that lower leptin levels here.
To learn more about normal leptin levels and what this hormone does in the body, read the first part of this series.
This post will focus on the dangers of high leptin. Elevated leptin levels are associated with obesity, overeating, and inflammation-related diseases, including high blood pressure, metabolic syndrome, and heart disease .
Leptin acts as a signal to the brain to inhibit food intake and enable the storage of surplus calories (in fat cells).
At the same time, it protects non-fatty tissue from fat overload. Increased leptin is associated with higher body fat mass, a larger size of individual fat cells, overeating, and excessive hunger. In rodents, it increases energy expenditure by using brown fat for energy .
The more fat is present, the more leptin is produced. This feedback loop, when functioning normally, keeps body weight in homeostasis: eating more food increases body fat, which increases leptin secretion, which decreases appetite and increases energy expenditure .
High leptin levels are believed to be caused by, among other factors:
- Overeating [9, 10]
- Emotional stress 
- Inflammation [9, 12]
- Obesity 
- Pregnancy 
- Pre-eclampsia 
- Gestational diabetes 
- Sleep apnea 
If you believe that your leptin system is unbalanced, talk to your doctor about any underlying conditions which may require attention.
Leptin is an inflammatory marker, as it responds to inflammatory cytokines from fat tissues. Autoimmune diseases are associated with increased secretion of leptin . In terms of both structure and function, leptin resembles IL-6.
Multiple studies have demonstrated elevated levels of leptin in chronic inflammatory conditions .
Leptin increases were associated with greater fatigue scores in people with CFS. Some researchers believe that it plays a causal role in CFS; however, chronic fatigue is a controversial and poorly understood condition, and this conclusion is by no means unanimous .
It was also found to be necessary for Th1 dependent inflammatory processes, acting as a critical regulator of CD4 T cells .
The effect of leptin polarizing T cells towards a Th1 response seems to be mediated by stimulating the synthesis of IL-2, IL-12, and IFN-gamma (all Th1 cytokines) and inhibiting the production of IL-10 and IL-4 [31, 32].
Th1 dominance correlates with excess leptin in this study of dialysis patients . If you’re Th2 dominant, it doesn’t mean leptin isn’t causing problems. It simply means that it’s causing different problems.
Mast cells in the human skin, lungs, gut, and the urogenital tract contain leptin and leptin receptors , suggesting that leptin communicates with mast cells.
It seems like leptin causes mast cells to be more inflammatory .
In metabolic syndrome patients, there was a positive correlation between leptin levels and the number of fat tissue mast cells, suggesting that leptin may stimulate mast cells .
Leptin correlates with (probably increases) mast cell activation in children with asthma who exercised .
Leptin promotes the growth and spread of cancer. This is one reason why obesity is considered a risk factor for cancer .
It increases angiogenesis by increasing vascular endothelial growth factor (VEGF) levels.
In a study of 3 fibromyalgia patients, they reported higher pain levels on days when they had increased leptin in their blood. A cohort study of 5,600 postmenopausal women showed similar results .
It is secreted by the stomach and enters the small intestine. Several studies have shown that leptin interferes with the absorption of some nutrients.
On the one hand, I could see this being both bad and good. If it blocks the absorption of glucose and amino acids, it can help weight loss.
However, blocking glucose uptake gives a better chance for SIBO to arise or for malnutrition from not absorbing amino acids.
Many researchers have argued that chronically high leptin levels can lead to leptin resistance, much like chronically high insulin levels can lead to insulin resistance. Symptoms of leptin resistance include :
- Weight gain and difficulty losing weight
- Urge to snack soon after meals
This post goes into more detail about leptin resistance.
When stressed, the body releases leptin, and increased leptin is associated with increased consumption of comfort foods .
A diet low in carbohydrates and fat may reduce leptin release .
Short-term fasting decreases leptin (24-72 hours) .
- Endotoxin in both rodents and humans leads to increased leptin levels [65, 66].
- Inflammatory cytokines such as TNF/IL-1 increase leptin [67, 68].
- Interferon-gamma and LPS mixture in fat cell cultures raises leptin .
If you are suffering from inflammatory symptoms, especially if they persist for more than two weeks, talk to your doctor about possible underlying causes of this inflammation.
Sleep apnea is linked to increased leptin in obese people. In one study, leptin levels returned to normal after CPAP treatment .
All the following have decreased leptin in various studies. However, these do not present appropriate strategies for decreasing leptin and improving health.
- Adrenaline, Norepinephrine, and Dopamine (catecholamines) 
- Thyroid hormones (T3/T4) 
- Testosterone  and androgens 
- cyclic AMP  – you can increase cAMP by taking forskolin.
- Nitric Oxide in fat cell cultures. This would translate to making sure you have good circulation 
- PPAR alpha and PPARgamma