Fat Chance: Being Slightly Overweight Is Actually Good For Your Health?

With the growing number of overweight people around us, obesity is slowly but surely becoming socially acceptable. Nobody is surprised by rather fat models, singers and TV presenters anymore. In fact, many people argue that being a bit overweight, particularly after a certain age, is perfectly normal. Are they correct?

Some surprising recent scientific findings do fly in the face of classic medical concepts about the norms of body weight. It appears that a bit of fat can indeed bring some benefits, not only problems.

BMI As An Approximate Measure Of Health

Body mass index (BMI), also known as the Quetelet index, is a parameter indicating whether someone is at a normal weight, underweight, overweight, or obese. It measures weight in relation to the individual's height and gives a certain score. Depending on this score, a person is classified into one of four weight categories:

1. Underweight: BMI below 18.5
2. Normal weight: BMI of 18.5 to 24.9
3. Overweight: BMI of 25 to 29.9
4. Obesity: BMI of 30 or higher

Excessive BMI may increase the risks of many health problems, such as diabetes mellitus type 2, hypertension, angina pectoris, heart disease, heart and brain strokes, certain types of cancer, sleep apnea, kidney disease, osteoarthritis, fatty liver disease, pregnancy problems such as pregnancy hypertension and diabetes, and increased risk of cesarean delivery.

For instance, professional athletes and bodybuilders in particular often appear to be overweight on the BMI scale. However, their higher BMI scores are linked to a higher muscular mass, rather than fat. So BMI is a measure more suitable for an “average Joe”.

How Does Body Fat Benefit Your Health?

However, recent studies have revealed that being slightly overweight may, in fact, improve a person's health and even lower their risk of mortality. Researchers discovered that an enzyme called nicotinamide phosphoribosyltransferase (NAMPT) secreted by the body's fat tissue controls the energy level in the brain and its response to a lack of food. They concluded that there may be an optimal amount of body fat for maximizing health and longevity. However, scientists still do not know what amount of fat is good, and how other body parameters play their role in conjunction with fat. Many studies reported that as we get older, people who are slightly overweight tend to have fewer health problems, especially a lower risk of dementia, and also a lower mortality rate.

Scientific findings point to the importance of NAMPT in producing a vital cellular energetic compound called Nicotinamide Adenine Dinucleotide (NAD), and in controlling the metabolism and aging processes. 

READ The Fat Acceptance Movement: Why Fat Shaming Has To Stop

Mouse studies have shown surprising results. Mice were raised with a deficit of NAMPT, and, as expected, the energy levels in their fat tissue were reduced. The effects on other tissues like liver and muscle were not significant, but there was a notable effect on the hypothalamus, an important part of the brain that plays a role in regulating body temperature, sleep cycles, heart rate, blood pressure, thirst and appetite. Low levels of NAMPT in fat tissue of mice resulted in low energy levels in the hypothalamus, and lower physical activity compared to mice without this defect.

How Your Fat Tissue's Biochemicals Control Your Energy Levels

The team performed an opposite experiment in which mice were triggered to produce higher than normal levels of NAMPT in fat tissue. These mice were much more physically active, especially after fasting, compared to normal control mice. Researchers also found that physical activity in mice with low levels of NAMPT in fat tissue can be improved with NMN injection (NMN — nicotinamide mononucleotide, an enzymatic product of NAMPT). 

According to researchers, the "NAMPT signal from fat tissue may serve as a survival mechanism", and "therapy with NMN might be a possible treatment for diseases and conditions associated with aging".

Slightly Overweight People Have A Lower Mortality Rate

One big study conducted in United States and published in the Journal of the American Medical Association investigated the relative risks of mortality associated with different BMI ranges. In this study, the obesity category (BMI > 30) was associated with 111,909 excess deaths while the underweight category (BMI <18.5)  was associated with 33,746 excess deaths. 

Being overweight (BMI 25-30) was not associated with any increased mortality. Both underweight and obesity BMI values, particularly higher levels of obesity, were associated with increased mortality relative to the mortality rate of people in the normal weight category. Because of improvements in public health and medical care, the impact of obesity on mortality may have decreased over time.

Being Overweight Reduces The Risk Of Dementia

A recent cohort study suggests that overweight people are less likely to develop dementia. Researchers analyzed the medical records of nearly two million people (aged 40 years and above) in whom BMI was recorded between 1992 and 2007. Results showed that underweight people (BMI <20) had a 34 percent higher risk of dementia, compared with normal weight people. The incidence of dementia continued to fall for every increasing BMI category. 

Overweight people with a BMI of 25 to 29 had an 18 percent lower risk of dementia, and very obese people (BMI >40) had a 29 percent lower dementia risk than people of a normal body weight. Being underweight in middle and old age carries an increased risk of dementia over two decades. Results contradict the commonly accepted theory that obesity in middle age might increase the risk of dementia in old age. However, these findings need further investigation.

Slightly Overweight People Are More Resilient

There are also statistical findings which show that those who are overweight or moderately obese better tolerate various health problems. For instance, diabetes patients with normal weight are twice as likely to die compared to those who are overweight or obese. Heavier dialysis patients have a lower chance of dying than those who are of normal weight or underweight. Mild to moderate obesity poses no additional mortality risks to those already suffering from heart disease, and obesity can help people with certain cancers to live longer. The explanation for that may be that not all fat cells are equal and might have different characteristics. 

For example, belly fat tissue can release fatty acids and inflammatory compounds into the bloodstream leading to a higher LDL — bad cholesterol, blood glucose and blood pressure.

READ Can You Be Healthy And Obese?

There is no doubt that becoming heavier and heavier must, at some point, damage health and reduce life expectancy. The benefits mentioned above sound good, but they are associated only with being slightly overweight, not obese. Being too heavy is hardly ever very healthy.