Frequently Asked Questions about Leptin
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Human Effect Matrix
The Human Effect Matrix looks at human studies (it excludes animal and in vitro studies) to tell you what supplements affect leptin
|Grade||Level of Evidence [show legend]|
|Robust research conducted with repeated double-blind clinical trials|
|Multiple studies where at least two are double-blind and placebo controlled|
|Single double-blind study or multiple cohort studies|
|Uncontrolled or observational studies only|
Level of Evidence
? The amount of high quality evidence. The more evidence, the more we can trust the results.
Magnitude of effect
? The direction and size of the supplement's impact on each outcome. Some supplements can have an increasing effect, others have a decreasing effect, and others have no effect.
Consistency of research results
? Scientific research does not always agree. HIGH or VERY HIGH means that most of the scientific research agrees.
|Minor||High See all 3 studies|
|Notable||- See study|
|Minor||- See study|
Scientific Research on Leptin
Leptin equates to a level of "available energy" for your body
Secreted by your fat cells (specifically white fat cells)
In rats, obese mice had no leptin. Following injection with leptin rapid fat loss occurred.
Rage over leptin as the miracle weight-loss hormone
Contrary to rats, overweight human beings had high leptin levels
Overweight people had developed resistance to leptin (similar to insulin resistance)
Essentially the signal from leptin to brain was broken somewhere
Injecting overweight humans with leptin provided no real weight loss
Leptin scales with subcutaneous fat (higher in woman) (Inversely, insulin scales with visceral fat, higher in men)
Estrogen seems to increase response of leptin
Leptin levels do not change quickly (can take hours)
Males below 10% bodyfat have almost no leptin in their bloodstream
Women have 2-3x leptin compared to men with equal BF%
Leptin seems to respond directly with carbohydrate metabolism in fat cells
Responds to both over and under-feeding
After a week of dieting, leptin drops 30-50%
Short-term carb overfeeding can bring leptin levels up (faster than fat is gained)
Only responds to carb-intake. Overfeeding on fat does not produce a similar response
Refeeds are used for both leptin and insulin
Leptin basically tells your body:
- How much fat you are carrying
- How much you are eating
Leptin is involved in a lot of stuff, including:
Too much body fat also impacts libido negatively due to insulin resistance
Levels are critical for puberty and fertility
Need a minimum level of fat for puberty. Childhood obesity -> higher leptin levels -> earlier puberty
Without enough leptin ("energy"), body decides reproduction not as important, shuts down reproductive system
Raising leptin brings back reproductive function without weight gain
Leptin is basically a safeguard from starving. With not enough "energy" body slows itself down
Lower levels of leptin could also impact dopamine signalling (aka increased resistance)
Existing fat levels matter. Losing 5% of BF at 30% BF does not trigger the same response as losing 5% of BF at 10% BF
Low leptin levels also make it hard to feel satiated
Conversely, in the short term, leptin tells your body it is full
As a supplement, leptin has to be injected. Pretty much impossible to get and very expensive
Best way to raise leptin is a high carb/high calorie refeed of at least two meals (eg lunch + snack).
Blood triglycerides seem to be cause of resistance (lower in high fat diets)
Insulin (not excessive amounts) and epinephrine increase leptin transport
insulin stimulates leptin release
Inflammation (omega 6/3 ratio) also increases leptin resistance
Refeeds should be high carb, moderate protein, low fat
Post workout is optimal time
Eg, Mark Sisson recommends 250-300g. Martin Berkhan targets 100-150g.
Short term cortisol increase can help leptin levels
Intermittant fasting (IF) is possibly positive - during fasting it falls, but breaking fast/refeed elevates it
In one study, mean leptin levels are increased. In a Ramadan study, the mean was the same
High amounts of fructose increases leptin resistance
- Melanson KJ, et al. Effects of high-fructose corn syrup and sucrose consumption on circulating glucose, insulin, leptin, and ghrelin and on appetite in normal-weight women. Nutrition. (2007)
- Monsivais P, Perrigue MM, Drewnowski A. Sugars and satiety: does the type of sweetener make a difference. Am J Clin Nutr. (2007)
- Soenen S, Westerterp-Plantenga MS. No differences in satiety or energy intake after high-fructose corn syrup, sucrose, or milk preloads. Am J Clin Nutr. (2007)
- Melanson KJ, et al. High-fructose corn syrup, energy intake, and appetite regulation. Am J Clin Nutr. (2008)
- Stanhope KL, et al. Twenty-four-hour endocrine and metabolic profiles following consumption of high-fructose corn syrup-, sucrose-, fructose-, and glucose-sweetened beverages with meals. Am J Clin Nutr. (2008)