The Stubborn Fat

Author :Aditya Mahajan, Assessment Team, INFS

Key points:
• Men accumulate visceral fat around the mid-section (apple pattern)
• Women accumulate subcutaneous fat around their hips and thighs (pear pattern)
• Though subcutaneous fat is more difficult to mobilize than visceral fat, greater visceral fat accumulation is found to be linked with obesity-related health issues.
• Women lose fat slowly than men, but they are more likely to survive starvation.
Keywords: Fat, subcutaneous, pear-shaped, women, stubborn fat.

 

Introduction:
As we discussed in the INFS health series for adolescents, body fat increases with the age [1] and both males and females have similar body composition till puberty, but post-puberty males gain more lean body mass and female gain more body fat. On an average, an adult female caries 10-12% more fat than an adult male. Also, there’s a clear distinction in the fat distribution patterns. In this article, we have covered the gender differences in the fat distribution and its implications.

Apples and pears:
One thing you must have observed that fat men and women don’t look same usually. Men tend to store more visceral fat in the intra-abdominal cavity (android obesity) whereas women store more subcutaneous fat near gluteal/femoral depots (gynoid obesity) [2-4]. This can be attributed to the difference in the hormones: higher testosterone/cortisol in men and Estrogen/progesterone in women [5]. So higher testosterone levels tend to promote visceral fat accumulation whereas higher Estrogen level promotes higher subcutaneous fat deposits (also probably the reason women suffer from cellulite more than men!). This type of fat distribution is commonly referred as apple and pear shapes.

Now excess visceral fat not only makes you look unattractive, it also increases the inflammatory response and cause several health problems. Android obesity is found to be linked with the greater risk of insulin-resistance related states, diabetes, cardiovascular diseases etc [6]. This is why women are at a much lower risk of heart-related diseases until after menopause, after which the hormone level and therefore the fat distribution also changes.

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One important consideration is that your body fat is a store for energy. So, in case of insufficient food (as in during dieting or famine), this stored fat is mobilized to provide energy to the body. Now, another form of energy storage is carbohydrates, but its storage capacity is limited whereas even the fairly lean individuals might store 100000 calories of fat, which should be enough to sustain them for weeks or months without any food.

Women preferentially store this fat in their lower body in preparation for pregnancy and being used in the later stages of pregnancy and during breastfeeding. The other important contributing factor to female’s body fat distribution could be sexual selection and attraction, providing the curves and other female characteristics.

Losing fat with a pear-shaped body​
Women tend to store more subcutaneous fat than the visceral fat. Now, visceral fat is metabolically more active than subcutaneous fat i.e. it is relatively easier to mobilize the visceral fat than subcutaneous fat though this also depends on the area being examined. The reason for the stubborn fat in lower body in females is the poor blood flow to the fat cells and a higher number of inhibitory alpha-adrenoceptors than beta-1,2 adrenoceptor (almost 9 times) which inhibits the lipolytic effect of catecholamines [7]. So, this is why women lose fat slowly than men.

Tackling the stubborn fat:

  1. Training (resistance and cardio) has shown to be beneficial in improving the blood flow to the fat cells and increasing the catecholamine levels [10]
  2. Fasting also improves the blood flow [8], but since fasting forever is not feasible, low carbohydrate diets (<100g) have been found to mimic many of the effects as of fasting. Low carbohydrate diets also reduce the activity of alpha receptors [9] which inhibits the catecholamines action. In fact, low carbohydrate diets were found to have a fat mobilizing effect on the lower body. This suggests that low carbohydrate diets could be beneficial when dieting to low body levels (<18% body fat for females)

CONCLUSION

Men generally have more intra-abdominal fat than women, and women have more subcutaneous fat in their hips and thighs than women though in certain cases (such as PCOD, overweight women etc) this fat distribution may also change. Several studies have reported a correlation between visceral fat deposits and several health issues.
Since visceral fat is more metabolically active than the subcutaneous fat, there is also a difference in the relative rate of fat loss between the two genders. Though women tend to lose slower than men but they even can achieve low %body fat (12-15) naturally through right nutrition and training.

References:
1. Kotani K, Tokunaga K, Fujioka S, et al. Sexual dimorphism of age-related changes in whole-body fat distribution in the obese. Int J Obes 1994; 18: 207-12.
2. Kvist H, Chowdhury B, Grangard U, et al. Total and visceral adipose-tissue volumes derived from measurements with computed tomography in adult men and women: predictive equations. Am J Clin Nutr 1988; 48: 1351-61.
3. Sjostrom L, Rissanen A, Andersen T, et al. Randomised placebo-controlled trial of orlistat for weight loss and prevention of weight regain in obese patients. European Multicentre Orlistat Study Group. Lancet 1998; 352: 167-72.
4. Vague J. La différenciation sexuelle: facteur déterminant des formes de l’obesité. Presse Med 1947; 339-40.
5. Krotkiewski M, Bjorntorp P, Sjostrom L, et al. Impact of obesity on metabolism in men and women. Importance of regional adipose tissue distribution. J Clin Invest 1983; 72: 1150-62.
6. Lemieux S, Després JP, Moorjani S, et al. Are gender differences in cardiovascular disease risk factors explained by the level of visceral adipose tissue? Diabetologia 1994; 37: 757-64.
7. Williams, Christine M. “Lipid metabolism in women.” Proceedings of the Nutrition Society 63.1 (2004): 153-160.
8. Gjedsted, Jakob, et al. “Effects of a 3‐day fast on regional lipid and glucose metabolism in human skeletal muscle and adipose tissue.” Acta physiologica 191.3 (2007): 205-216.
9. Gesta, Stéphane, et al. “In vitro and in vivo impairment of alpha2-adrenergic receptor-dependent antilipolysis by fatty acids in human adipose tissue.” Horm Metab Res 33.12 (2001): 701-7.
10. Dimsdale, Joel E., and Jonathan Moss. “Plasma catecholamines in stress and exercise.” Jama 243.4 (1980): 340-342.

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