Fat facts

So hopefully you're on-board with the benefits of increasing dietary fat and understand that its not eating fat that causes obesity, heart disease, etc. But what about the actual fat that we are carrying around? The majority of us spend a lot of time and effort trying to reduce it but what is it, what does it do, and should we try to shed every last gram of body fat? 

The basics

Stored fat is stored energy and historically for us humans it has been a powerful adaptation. Without the capacity to store energy in the form of fat we couldn't have survived through millions of years of evolution. We needed the capacity to store energy to survive periods of famine, and fat is a very sefficient way to do this. Even a relatively lean 75kg man typically has over 100,000kcal stored in the form of fat, that's enough energy to run over 38 marathons! If we had to store this energy as glycogen, our body weight would increase by 40-60kg as glycogen is less energy dense and is stored in combination with water. 

Fat is more than just stored energy though, it's actually an organ and an important one that is needed by the body for a wide variety of functions. The amount of required body fat for the body to stay living (essential body fat) is around 3% for men and 9% for women. Drop below these percentages and problems will occur. Women in particular start to see menstrual irregularities when their body fat drops to single digits which will put them at risk for problems such as osteoporosis and should be avoided at all costs.

Finally we have two types of fat tissue in our bodies, brown fat and white fat, which both serve very different functions.

White Fat

White Adipose Tissue (WAT) is our body’s main type of fat and is found under the skin (subcutaneous fat) and around our internal organs (visceral fat). It is our largest energy reservoir and does a great job of insulating and cushioning us when we fall or in times of stress. 

Although white fat has a bad reputation, our bodies need it as it serves many purposes. It is a major endocrine organ, producing one form of estrogen as well as leptin, a hormone that helps regulate appetite and hunger. It contains sensors for multiple key hormones such as  insulin, growth hormone, adrenaline, and cortisol, and it secretes many important hormones and immune-modulating signals that affect your metabolism and immune system. Finally it is our thermal insulator.

Excess White Fat

In women excess white fat is mainly found around the hips, thighs, buttocks, and breasts until perimenopause, when fat is redistributed to the abdomen as well. Men tend to gather excess fat primarily in the belly region most of their lives. 

Problems can arise if you have too much of this type of fat and it is well documented that excessive white fat, especially visceral fat, can lead to an increased risk of metabolic dysfunction, heart disease type 2 diabetes, breast, colon, esophageal, gall bladder, and pancreatic cancer. It’s also associated with sleep apnea, and physical disabilities such as knee arthritis.

Brown Fat

Brown adipose tissue (BAT) is composed of several small lipid droplets and a large number of iron-containing mitochondria (the cell’s heat-burning engine). The iron, along with lots of blood tiny blood vessels, gives this fat its brownish appearance. Brown fat is usually found in the front and back of the neck and upper back. The purpose of brown fat is to burn energy in order to generate heat. Brown fat is derived from muscle tissue and is found primarily in hibernating animals and newborns. After life as an infant, the quantity of brown fat significantly decreases and decreases further with ageing. It is also thought that in addition to burning energy to keep us warm, brown fat also helps maintain stable blood sugar levels by burning any excess blood sugar. This explains why adults who have comparatively more brown fat tend to be younger, slender, and have normal blood sugar levels. 

How to create more brown fat

So while white fat is important it can be problematic in excess, and the majority of us probably wont benefit from increasing WAT levels. There are potentially benefits to be had though by increasing our levels of BAT. Research suggests the following methods all either help to increase BAT levels, or activate existing BAT:

1. Exercise of any form helps to convert existing WAT to the more metabolically active BAT.
2. Cold exposure and exposing yourself to the cold regularly, such as exercising outdoors in the wintertime or in a cold room. Lowering the temperature in your living and working spaces has been shown to increase the levels of BAT. The longer the duration of exposure the more effective this method is but some benefit can still be gained by a simple daily cold shower.
3. Satiety.  We rely on hunger-regulating neurons in the brain to notify us when we've had enough and these same neurons also  encourage WAT to convert to BAT. Research suggests that eating too few calories prevented this conversion, while eating just enough to satisfy hunger, prompting the action of the neurons, caused the conversion. Other research shows that over-consumption not only increases WAT it also interferes with BATs ability to burn calories.
4. Melatonin production. Not only does the hormone melatonin help regulate our sleep-wake cycle, but it also increases the presence of BAT. Rather than supplementing with melatonin it's best to stimulate your body's own natural production by avoiding nighttime exposure to light from TVs, computers and other screens, getting sunlight exposure during the day, and loading up on melatonin-rich foods, including almonds, tomatoes, tart cherries, cardamom, and coriander. 

Fat levels

A healthy range of total body fat for women is thought to be 15 to 30 percent and 15 to 25 percent for men, there are several ways to measure your total body fat percentage, including:  

• Body Mass Index
• Calipers
• Bioelectrical impedance scales
• Hydrostatic weighting
• DEXA (Dual-Energy X-Ray Absorptimetry)
• Air-displacement plethysmography

Measurement of BAT is currently in its infancy with researchers using CT imaging and MRI protocols.

Conclusion

Too much white fat is not a good thing but that doesn't mean that all body fat is bad. Sufficient levels of white and brown fat are essential for a health and longevity, and furthermore there are a number of benefits to be had from increasing our levels of brown fat.