Leptin and Insulin cause Weight Gain

Leptin is a hormone created in our fat cells discovered in 1994 name after the Greek word leptós meaning thin and instructs our brain how to regulate food intake. 1

It is the combination of both high Insulin and high Leptin that naturally drives weight-gain. 2

It has been discovered that high Insulin blocks the signalling to the brain from Leptin saying that we have enough storage in our fat cells and holds onto the weight and makes us want to eat more.

As highly processed carbohydrates rise insulin (or injected insulin) causes that Leptin signaling to never reach the brain, so the brain tries and make up for the energy deficit by driving us to consume excess carbohydrates into our fat cells.

But food is only one of many factors that alters Leptin signalling as light has a huge part as summer is designed for you to make fatter and the long light cycles reduces evening melatonin , which pushes back the usual nighttime peak in prolactin, which causes an abnormal resistance to Leptin, which induces hypothalamic NPY and subsequent carbohydrate craving. 3

So in short the longer the light cycles it primes to store weight sadly with the increased usage of artificial lights mobile phones and tablets we have created a perfect year round summer.

So the key / holy grail to weight loss is to keep insulin low and Leptin high but this combination is rare in nature and is to protect our fat stores, I’ll write a more detailed post on how you can get that combination.

The video below from Dr Robert Lustig shows the vicious cycle on why insulin and Leptin causes obesity .



  1.  ncbi.nlm.nih.gov/pmc/articles/PMC3424452/
  2. Friedman et al discovered Leptin in 1994, and demonstrated that this hormone, the product of the obese (ob) gene, was produced in white adipose tissue and served as the peripheral signal to the central nervous system of nutritional status.
  3. caloriesproper.com/summer-is-fattening-dont-do-it-in-winter/