Have you cut your calorie intake and reached a weight loss plateau anyway? Have you counted your calories and done the math and can’t make sense of why weight loss is so slow or not at all? Answers may lie in understanding the difference between white, brown, and beige fat.
Brown Adipose Tissue (Brown Fat)
Adults have three types of fat: brown, white, and beige. White fat is what most people are trying to lose because they have excess weight and often metabolic problems associated with it. White fat is what most people think of when they think of fat. It stores energy as triglycerides. It is often in the trunk and abdomen. Brown fat is much less common in human adults. Its job is to keep vital organs warm. It does not produce energy, it produces heat. It is located around vital organs and in places where there is more surface area, such as the chest and groin. Brown fat is easy for your body to burn and activate. The fat cells are small, surrounded by many blood vessels, and there are many organelles called “mitochondria”. These are known as the “powerhouse of the body.” They are what actually burn the fat. So, when the body needs heat, the mitochondria “turn on”, activate the brown fat, and burn the energy stored in them and dissipate the heat into the blood. It looks brown because of all the mitochondria.
White Adipose Tissue (White Fat)
By contrast, white fat has several key differences. Each fat cell is large and there is a shortage of blood vessels relative to the volume. There are much fewer mitochondria. This all means that the infrastructure to “turn on” the fat and actually burn it is sparse. To make matters worse, white fat is the largest endocrine organ in the body, producing chemicals called adipocytokines that cause further metabolic dysfunction. White fat is the predominant form of fat in the disease of overweight and obesity.
Beige Fat
The third type of fat is beige fat, which is in between white fat and brown fat. As you might guess, this “in-between” adipose is what can happen to white fat to make it easier to burn and turn into energy. In a process called “beiging”, your body extends more blood vessels into white fat to be able to activate it metabolically. Beiging of white fat may be the key to unlocking this storage of excess energy and reducing the metabolic dysfunction that comes from it and can affect the entire body. So, if you are finding that you are not losing weight despite cutting calories, how can you turn white fat into beige fat so it can be burned?
Exercise
While there are many misconceptions about exercise and weight loss, one that is not talked about much is how it is a major lever to pull to “beige” white fat. Most of the time, exercise is considered part of the “calories in, calories out” equation, which has many potential pitfalls (discussed in other blogs). But, exercise certainly seems to kick off a cascade of events that changes everything else about how the body feels, functions, and responds to other interventions. Studies show that both aerobic exercise and resistance exercise can beige fat, but it takes at least a moderate intensity to do the trick. Studies showed it was at 60% of the VO2 max for an hour, five days a week, that caused the changes from white fat to beige fat. If you are limited on time, high intensity, as opposed to moderate intensity, can cause changes in shorter amounts of time. But, simple physical activity, such as steps, which do not stress your body and raise your heart rate, are probably not enough to cause changes in your physiology. The good news? If you feel like you have barriers to exercise, whatever is challenging for you is fantastic.
Cold
While you may not be able to use cold temperatures as much as exercise from a practical perspective, I think there are a few important opportunities from knowing how colder temperatures can cause beiging of white fat. Studies compared exercising at room temperature versus heated rooms and measured markers of beiging of fat. Those who exercised in room temperature had higher signs of beiging. I think this makes sense, since the primary function of brown fat is to produce heat to maintain body temperature. This may also explain the link between the pervasiveness of climate control and the increase in body weight across society. We tend to always be in a climate controlled environment, so our body does not need to expend any energy maintaining body temperature, and it may even “turn off” the system for doing so. There are studies on keeping the thermostat a little lower for preventing weight gain. As I think of some trendy exercise gyms and workouts advertising hot temperatures for burning more calories, in the context of these studies, it makes me think those just increase your heart rate and make you sweat while you are there, but may actually be worse for beiging of white fat.
Outside of exercise, “cryotherapy” may tap into the physiologic benefits of cold. You don’t need a fancy cryo machine, either. Simple things you can do are ending with a cold shower, going for a walk outside even in the cold, or leaving a layer off in the house and turning down the thermostat.
Ketones
Ketones are produced when fat is used for fuel. In human physiology, glucose and carbohydrates are “easier” and more efficient to use for fuel. Using fat for fuel instead may have two advantages: it is less efficient (which is good when you are trying to lose weight), and it produces ketone bodies which can cause beiging of white fat. There are two ways to get more ketones: a ketogenic diet or taking supplementary ketones. A ketogenic diet requires consuming low carbohydrates consistently. The ketogenic threshold can vary from person to person, but is under 20 grams a day of carbohydrates at the low end and under 100 grams on the high end. Remember, while protein and fat are essential to the human diet, there is no physiologic requirement for carbohydrates in the diet for a human to survive. Ironically, the typical American Diet is 60% carbohydrate. Perhaps this is a main reason for the epidemic of obesity? Currently, the big pharma drug companies are making an absurd amount of money and using the behemoth healthcare industry as its partner, to convince Americans they have an “incretin defect” that requires their drug to treat or they can’t lose weight. While I certainly acknowledge the irrefutable fact that not everyone has the same metabolism and there are very strong genetic causes of obesity that benefit from treatment with a medication just like any other disease, I think it is equally irrefutable that there are modifiable environmental and societal factors that make everyone more susceptible to metabolic dysfunction and we can not ignore or fail to address all of the things that are leading to the decline of the health of Americans.
Lactate
Lactate is another acid, like ketones, that promotes the beiging of fat. Where does lactate come from? Lactate is produced when muscles function without oxygen. Lactic acid is what makes your muscles burn when you work so hard at exercise that your cardiovascular system can not keep up and deliver oxygen to the muscles fast enough. This makes the muscles switch from aerobic metabolism, which requires oxygen, to anaerobic oxygen, which does not. Each person has an “anaerobic threshold”, which is expressed as liters of oxygen per kilogram per minute. There is usually a heart rate above which you are using anaerobic metabolism. The gold standard way to determine this is a VO2 max test, but many current wearable fitness watches will calculate your VO2 max after you have been wearing it and exercising with it on for a while. You can also feel it. When your muscles burn, you are above your lactate threshold. They also studied exercise in low oxygen environments, but this does not sound like a good idea from a safety perspective.
How can you use this information? Many times, people have been trying to lose weight by exercising. Overwhelmingly, nutrition and diet are the most important first things to address. Focus at first on the food. Do not count calories burned during exercise and add those back to your diet unless you are exercising at very high volumes and do not have excess fat to burn. Frequently, there is a point at which weight loss plateaus despite the diet. At this point, exercising at a target heart rate and volume with both aerobic and resistance exercise may be the “make it or break it” lever to pull. Throughout the process, consider allowing your body to use its natural systems to maintain body temperature (within reason). A ketogenic diet also differs from a calorie restriction diet by potentially leading to beiging of fat, but remember you have to control calories at the same time.
Aging
White fat increases with aging, even while body weight stays the same. Body composition changes as people change include the loss of lean body mass, decreased brown fat, and increased white fat. This is probably why people notice their metabolism acts differently as they get older. Strategies to maintain skeletal muscle mass, reduce white adipose tissue, and increase beige fat can slow this aging of the metabolism. The good news? It is not time itself, and there are things you can do that make a HUGE difference.
Medications
There are many medications that lead to weight gain or prevent weight loss. Anecdotally, I have observed people's body composition change dramatically over relatively short periods of time when they started new medications, even separate from their BMI. Then, when they cut calories and move more, nothing happens. Is the medication increasing white fat? I don't think the research has been done yet.
Hopefully, this blog has shed light on just one way in which body composition regulation is not just “calories in, calories out” and while a simple calorie deficit diet plan does not work for everyone. As always, remember that some people have metabolic disorders that benefit from medication and/or surgery to treat to reach a healthier weight. This blog should be one example of why not everyone's body responds in the same way to the same thing, even if they start at the same BMI. There should be no stigma, shame, or bias in recognizing and acting on that fact. If your weight is contributing to any health concerns, the important thing is to talk to a doctor trained, educated, and experienced in weight management to get the best of all treatments, including medications and/or surgery. It all works together, and medication or surgery can be the missing link between lifestyle change and results. But, they certainly are not the full picture, either. It all works best when it works together. If you have health concerns, don't "go it alone." It is much more complicated that we've been led to believe, and we are just beginning to do the research to understand.
Take Back Your Beiging,
Valerie Hope-Slocum Sutherland, MD
