The mechanisms behind fat storage are complex, if it was simple then everyone would be thin for their wedding (if that’s the desired effect), strip their love handles or have rippling six packs that whole year round. The reality of the matter is this, fat is stubborn, but in the same token it’s stubborn for damn good reason. Fat has a critical role in maintaining homeostasis, our bodies need fat for hormonal communication, cell integrity and energy (to name a few functions). So although fat may be stubborn, it’s trying to hang around for good reason, truth is though…we don’t want or need it around our butts, hips and stomachs all year round, especially if you’re a bloke! So why for many people does fat simply refuse to go away, and what makes it so tough to lose in certain parts of the human body!? Let’s investigate…
The differences between male and females do not end at the obvious (breasts, genitalia, Adam’s apple etc); in fact those visible differences are just scratching the surface! Those visible differences are only visible because of genetic and hormonal variations, and these affect your weight (fat) and fat distribution. You may be familiar with the apple and pear shapes that men and women can have, the apple shape describes a round mid- section (around the stomach) whilst the pear depicts a lower distribution of weight (mainly fat). Men are more commonly an apple shape, whilst women are pears. This fat distribution phenomenon is no coincidence, it’s actually to do with a number of factors including child birth, blood flow and fat cell receptor distribution.
Child birth and fat distribution
The body is an amazing thing, it plans ahead even if you don’t. Evolution dictates that females store more fat around their hips, bum and thighs in anticipation of pregnancy. The extra fat around these areas help to insulate the impending foetus, but the consequence of this is that females have some difficulty losing fat around those areas! It’s by no means impossible, not even close, fat can be burned from those areas if you enter a controlled calorie deficit, train those areas and consume appropriate levels of macros (protein, carbs and fat).
Also known as the blood flow redux, blood flow is significantly lower in some areas of the body than others making it harder to burn fat from those regions of the body. A good way to test this is to touch an area of your body where you seem to burn fat faster than others, you should notice that it feels comparatively warmer than your bum, hips and thighs. In fact, some studies have suggested that blood flow is as much as 67% less in these areas. Studies noted that visceral fat has a very good blood supply and therefore disappeared a lot faster than subcutaneous fat that lies under the surface of your skin (particularly your stomach, hips, bum and thighs).
Poor blood flow can reduce fat loss because the lipolytic (fat burning) hormones responsible for fat loss (catecholamines such as epinephrine and norepinephrine) cannot readily reach those areas. As well as this, broken down fat stores are mobilised less effectively due to the poor blood flow, consequently they are not broken down for energy. But why is blood flow so poor in these areas!?
Alpha- 2 adrenoreceptors, blood flow and hormones
Resonance images show there to be less total blood vessels in the hips, bum and thighs, this obviously reduces total blood flow. Less obvious is the part Alpha- 2 adrenoreceptors might have to play in blood flow. Alpha- 2 adrenoreceptors are key because they encourage vasoconstriction i.e. narrowing of the blood vessels which reduces blood flow. Conversely, areas in the body that are high in beta- receptors have a better blood flow because these receptors encourage vasodilation i.e. widening of blood vessels. Theories also suggest that the lower body, particularly in women, is more sensitive to insulin which means lipolysis (fat breakdown) is reduced (insulin is anti-lioplytic).
Saunders, C; Limbird, LE (November 1999). "Localization and trafficking of alpha2-adrenergic receptor subtypes in cells and tissues". Pharmacology & Therapeutics 84 (2): 193–205.