Leptin: The Hunger Hormone

May 7th, 2012

Leptin: The Hunger Hormone

Robert H. Lustig, MD on UCTV Prime: The Skinny on Obesity

Another month has come and gone and it feels like just overnight we’ve entered my favorite time of the year:  summer! We’re already 1/3 of the way through the year!

One of my 2012 resolutions was to return to school. So, I enrolled in a science class to better understand the inner workings of the incredible human body. It’s true what Einstein said, "The more I learn, the more I realize I don’t know."  I’ve spent the past few months studying and the more I think I know what I need to know, my eyes are opened to so much more that I didn’t even know was there.  One of the areas about which I particularly feel this way is energy expenditure and appetite.

While most of us don’t give it much thought, our hunger and energy output are tightly regulated by hormones, or chemical messengers. Not those kind of hormones! There are other hormones that are communicating with the brain about when to eat, how much to eat, and how much to burn. In the 8-minute video above, Dr. Robert Lustig explains just how our appetite-regulating hormones can be hugely influenced by the foods we eat.

One of the hormones he mentions in this video is Leptin.  Unlike other hormones, which are made in endocrine organs like the pancreas or thyroid, Leptin is made in the fat cells.  Yep, that ungodly fat on your belly or butt is secreting one very important hormone. Its job is to monitor how much fat is stored in the adipose tissue.  When we have plenty of fat on hand, it lets the brain know by releasing Leptin hormone. The brain responds by suppressing appetite and increasing energy expenditure.  But, when the fat reserve is low, there is less Leptin reaching the brain and this triggers an increase in appetite and decrease in energy.

This is where it gets fun. So, if fat cells release Leptin, which signals an increase in energy output and suppresses appetite, then people carrying around extra bodyfat should have a plethora of Leptin flooding the brain & telling it to ramp up the metabolism and stop eating, right? Well, not exactly. They have plenty of Leptin to go around.  Too much, in fact, that the brain becomes resistant. It doesn’t hear the signal anymore and thinks there is a famine. So, what happens? Yup, you guessed it; appetite goes up even though the fat stores are filled to the brim. The whole vicious cycle starts all over again.

In the video, Lustig blames the "industrial global diet," namely, sugary foods & refined grains. Leptin-resistance has been linked to excess triglycerides, elevated stress hormones, and inadequate sleep. To read more about Leptin and it’s role in regulating weight, check out Jack Kruse, MD’s website. Jack Kruse is a neurosurgeon who was has done a lot of research on Leptin and who has himself lost somewhere around 140 lbs.

*Just watch the video If you don’t want to read this long post.