Let’s begin with the facts! There are several hormones in our body that promote fat burning, e.g. glucagon, thyroid hormones and adrenaline. When the pancreas secretes glucagon, the hormone enters the systemic circulation and reaches all our cells and turns on lipolysis. Thus local fat burning does not exist because these hormones have a lipolytic effect on the whole body (called systemic effect). That is a fact.
Let’s take an average woman, starting her college life. She starts to gain weight, around 20-40 pounds extra bodyfat. Along with her bodyweight her cupsize increases too. At one point in her life, she says „Enough!” and starts exercising and dieting. She starts to lose weight.
What will she complain about?
Answer: that her cupsize started to decrease first and her hip circumference (i.e. butt) last.
If we look at the tape measures we see that it’s true.
Now let me ask You this: What is this if not spot fat reduction?
Seems like we have a contradiction here… How can we resolve this conflict?
Well it’s pretty easy. The presence of fat burning hormones is only one component in fat burning. It’s necessary, but there are other factors as well.
Short-course in fat burning:
- Fat burning hormone binds to its receptor on the cell and starts a chain reaction inside the cell.
- The chain reaction results in the breakdown of triglycerides – to glycerol and free fatty acids – that make up the intracellular lipid droplet in fat cells.
- The glycerol and free fatty acids exit the cell to the interstitial space.
- The glycerol and free fatty acids from the intercellular space are delivered to the tissues by the blood and lymphatic circulation.
Now find a spot on your body where you tend to store excess bodyfat (ladies: buttocks, gentlemen: abs and love handles) and touch it. With your other hand find a spot where you store nearly zero fat and touch that too. What do you feel? The fatty spot is cooler. This is because subcutaneous fat insulates your body. How does it do that? It has poor circulation.
But circulation is crucial in fat burning. If an area has insufficient blood flow, fat burning will be at a very low level. Science shows that even the increase in blood flow during exercise is not enough to transport the glycerol and fatty acids broken down by the fat cells. Insufficient clearence of fatty acids, glycerol and other byproducts results in the inhibition of fat burning. Increasing blood flow at a certain area of the body can increase the amount of fatty acids released from the fat cells.
This sounds pretty good, but that’s not all, folks! Let’s examine what happens during exercise – take seated single leg extension. During muscle work we examine the subcutaneous fat „covering” the muscle (quadriceps). What we will find is:
- body fat stores adjacent to working muscles have higher blood circulation.
- these fat deposits release greater amount of glycerol and free fatty acids than fat deposits distant from the working muscle.
- lipolysis in these fat cells is greater.
(The experiments were executed exercising one leg and comparing it to the other.)
So what can we do with stubborn fat stores?
- Keep the area warm and increase circulation of the area: use clothing, and creams.
- Work the underlying muscles of the problematic area.
- Time the whole thing properly: though the presence of fat burning hormones is just one part of the lipolysis equation, it is mandatory! In terms of fat burning the most important hormone to control is insulin – low insulin results in lipolysis. (So, eating carbs before training will inhibit fat burning.[5,6])
So can you spot reduce body fat? Yes you can. Can you make up a training plan, that burns more fat from your butt or your abs? Yes you can. How should a training like this look? Well, that’s for another article….
- Adv Exp Med Biol. 1998;441:171-9.
Regulation of fatty acid delivery in vivo.
- Proc Nutr Soc. 1999 Nov;58(4):877-86.
Macronutrient metabolism of adipose tissue at rest and during exercise: a methodological viewpoint.
- Am J Physiol Endocrinol Metab. 2007 Feb;292(2):E394-9. Epub 2006 Sep 19.
Are blood flow and lipolysis in subcutaneous adipose tissue influenced by contractions in adjacent muscles in humans?
Stallknecht B1, Dela F, Helge JW.
- Obesity (Silver Spring). 2007 Sep;15(9):2245-55.
Sex differences in lipolysis-regulating mechanisms in overweight subjects: effect of exercise intensity.
Moro C1, Pillard F, de Glisezinski I, Crampes F, Thalamas C, Harant I, Marques MA, Lafontan M, Berlan M.
- J Sports Sci Med. 2004 Sep 1;3(3):106-17. eCollection 2004.
Dietary fat and sports nutrition: a primer.
- Clin Sports Med. 1999 Jul;18(3):485-98.
Role of fats in exercise. Types and quality.