Understanding Body Fat and Postpartum Fat Loss

Text/ Zeng Yongzhen

Doctors have found that obesity is closely related to the occurrence of cancer, so losing weight is not only for the sake of beauty, but also has positive health implications. For postpartum mothers to lose weight, the first thing to do is to lose fat. Before fighting fat, you need to understand the fat in your body. Only by knowing yourself and your enemy can you win every battle!

Dr. Yan Ronglang, who received his Ph.D. in tumor biology from the MD Anderson Cancer Center in the United States, worked in the Department of Radiation Oncology at Chang Gung Memorial Hospital after returning to China. He has been studying the mechanism of cancer for a long time and pointed out that obesity and the occurrence of cancer are closely related. Therefore, in order for postpartum mothers to lose weight, the first thing to do is to lose fat. This is not only for the sake of beauty, but also can reduce the risk of cancer in the future.

Definition of Obesity

Dr. Yan Ronglang said that body mass index (BMI) is a tool commonly used to assess obesity or not. It is calculated as follows:

BMI = weight (kg) / height2 (m)

The ideal BMI value for Taiwanese adults is 18.5≦BMI＜24; when BMI≧24, it means overweight, and ≧27 means obesity. However, this also needs to be judged in conjunction with the proportion of body fat (body fat percentage) in the body composition. For example, athletes or people who exercise regularly have a very high proportion of their body composition coming from muscles. Therefore, although the BMI value may exceed 30, if the body fat percentage is very low, there is no need to lose weight.

Body fat percentage

There are several ways to estimate body fat percentage. In addition to using a body fat meter, you can also estimate it by measuring your waist circumference:

Male body fat percentage calculation method:

Parameter a = waist circumference (cm) x 0.74; parameter b = (weight/kg x 0.082) + 44.74;

Total body fat weight = a–b, Body fat percentage = (Total body fat weight ÷ body weight) x 100%

Female body fat percentage calculation method:

Parameter a = waist circumference (cm) x 0.74; Parameter b = (weight/kg x 0.082) + 34.89;

Total body fat weight = a–b, body fat percentage = (total body fat weight ÷ body weight) x 100%

The normal body fat percentage for boys is about 15% to 25%, and for girls it is 20% to 30%. If the body fat percentage of adult males is greater than 25% and that of women is greater than 30%, they are still considered obese even if their weight and BMI values ​​are within the normal range.

waistline

Measuring waist circumference can help you understand the amount of visceral fat. The wider the waist circumference, the more visceral fat you have, which is more likely to cause chronic inflammation and various chronic diseases. Therefore, if a man's waist circumference exceeds 90 cm and a woman's waist circumference exceeds 80 cm, they are both considered to have excessive visceral fat.

Understanding fat

Regarding adipose tissue, Dr. Yan Ronglang has the following explanation: Human fat can be divided into two types, but their effects on health are completely opposite.

White adipose tissue

Visceral fat belongs to this category, and its main function is to store excess calories. This type of fat cell contains a single large fat globule, while the nucleus and cytoplasm are pushed to the edge by oil droplets, and there are very few mitochondria. Therefore, when white adipose tissue proliferates and hypertrophies, it is easy to develop moderate to wide-type obesity, causing chronic inflammation and other chronic diseases.

Brown adipose tissue

The main function is to produce heat to maintain body temperature. Since the temperature regulation center in the baby's brain is not yet developed and they are prone to die from hypothermia, they rely on brown fat to produce heat to maintain body temperature. The content of brown fat can reach 5% of body weight. The fat in brown fat cells is stored as multiple small and medium-sized oil droplets and is rich in mitochondria (1,000 times that of white fat cells). These mitochondria can metabolize fatty acids and release them directly as heat energy. Therefore, the more brown fat there is, the more it can consume excess calories in the body, which is beneficial for weight loss.

However, brown fat gradually decreases after we are born and has significantly degenerated by the time we reach adulthood; while white fat increases with age. Recent studies have shown that adults still have a small amount of brown fat, which is mainly distributed in the back of the neck, above the clavicle, near the shoulder blades, under the armpits, around the heart, spine and adrenal glands.

The relationship between obesity and chronic low-grade inflammation

Dr. Yan Ronglang said that when fat grows too fast and the expansion of adipose tissue exceeds the blood vessel supply capacity, fat cells will die due to lack of oxygen, which will attract macrophages and aggravate inflammation, forming a vicious cycle of inflammation and obesity.

Chronic low-grade inflammation, which has only gradually been understood by the medical community in recent years, is caused by incomplete repair of injured tissues during acute inflammation, which causes the inflammation to continue at a low level. This type of inflammation is not severe, and patients or doctors usually do not actively seek treatment, so the inflammation may continue for several years. If obesity exacerbates the chronic inflammatory response, or if long-term psychological stress, smoking and other bad habits are present, chronic inflammation may cause various chronic diseases (such as high blood pressure, diabetes, heart disease, cerebral stroke, Alzheimer's disease, Parkinson's disease, etc.), and may also induce cancer.

※The original article was published in the November 2013 issue of Mom & Baby Magazine.

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