During the last couple of years I’ve coached dozens of clients whose primary goal is to lose weight. I’ve also delved into the scientific literature on body fat regulation and written extensively on the topic. If there’s one thing this process has taught me, it’s that the general recommendation to restrict energy consumption and exercise more doesn’t work. Off course we have to reduce our food intake and/or expend more energy to lose weight, but this doesn’t mean that telling people to ‘eat less and move more’ is good advice. In the two following posts I’m going to summarize my take on things in a very concise manner. I’ll begin by explaining the fallacies of conventional weight loss advice and then outline what does work for fat loss in part 2. If you want more thorough information on the different topics, I recommend that you go through my more comprehensive articles.
Our understanding of overweight and obesity is constantly expanding, and it’s important to be humble in the sense that there’s still a lot we don’t know. However, if there’s one thing we’ve learned, it’s that gluttony and inactivity aren’t the only reasons why we get fat. While science slowly reveals new components essential to body fat regulation, the basic structure for understanding obesity, metabolic syndrome, cardiovascular disease and other ‘diseases of civilization’ will always be the same. Overweight and obesity result from a mismatch in the sense that we have strayed so far away from the ‘habitat’ we’re adapted to live in. The Organic Framework is an invaluable tool for analyzing human physiology and scientific studies, and also provides the foundation for designing an effective weight loss plan.
Overweight and obesity result from a perturbation of the homeostatic setpoint
Fat mass is biologically regulated (1,2,3). If we deliberately restrict calories and/or exercise more, areas in the brain that are responsible for regulating fat storage will trigger measures (e.g., interest in food, decreased metabolic rate, decreased body heat production) in an attempt to prevent fat loss and ‘defend’ the amount of body fat we carry (the fat mass setpoint) (1,4). Since these compensatory mechanisms can only prevent a certain degree of fat loss, we will start to lose weight. However, we will also experience all the classic symptoms of voluntary energy restriction, such as tiredness, hunger, and low metabolic rate. When we can no longer take the semi-starvation and start eating to satiety again, the body weight will creep back up towards the original starting point.
What we have to ask ourselves is this: Why does the brain ‘protect’ an elevated level of fat mass in people who are overweight and obese?
Leptin is a master hormone involved in regulation of body fatness
The hormone Leptin is produced in the body’s fat stores and allows the brain to control the size of these stores by regulating appetite, metabolic rate, thermogenesis, skeletal muscle work efficiency, etc. Since leptin production correlates with the size of the fat stores, people who carry a lot of fat mass produce more leptin than folks who are lean.
The hypothalamus in the brain is supposed to respond to high levels of circulating leptin by decreasing hunger, increasing energy expenditure and ramping up the use of stored energy, but poor leptin sensitivity associated with overweight and obesity prevents the leptin receptor in the brain from receiving a full leptin signal (5). So, although an obese person has a lot of leptin circulating in the body, the brain doesn’t respond properly to the signal (6).
It seems that one of the primary reasons why people gain fat and maintain an elevated level of fat mass is that the brain no longer responds appropriately to the negative feedback signal from fat cells (7).
Although leptin is far from the only factor involved, improving leptin sensitivity is a key component to losing weight. If we regain leptin sensitivity, the brain should respond to the high levels of circulating leptin and increased leptin signaling by decreasing hunger and increasing energy output. We eat less without deliberately restricting calories, and the body ramps up the use of stored energy.
To lose weight we have to attend to the factors that impair the energy homeostasis system
Two of the major factors associated with altered leptin signaling and weight gain are gut dysbiosis and highly processed food. Proinflammatory gut bacteria and increased intestinal permeability can potentially induce leptin resistance by allowing bacterial endotoxins to breach the gut barrier (8). This translocation leads to a state of chronic low-grade inlammation (endotoxemia), which potentially triggers leptin resistance in the hypothalamus and/or the nerves that carry information from the internal organs to the brain (9,10,11). While more studies are needed to elucidate this theory, I strongly believe it’s a major factor involved.
Highly rewarding food can also trigger a perturbation of the homeostatic setpoint in the sense that the brain’s mechanisms for regulating food intake and fat storage aren’t designed to handle processed, modern food. Products containing a wide spectrum of rewarding properties seem to trigger addictive processes in the brain and oppose the action of leptin (5.12,13).
Since foods that ‘overwhelm’ the reward center in the brain also alter the gut microbiota, it’s difficult to establish the relative importance of food reward and dysbiosis. I believe they are both essential, but tend to put more emphasis on bacteria as I think they could be the key. To lose weight we have to take care of these two components and also address the other factors that influence inflammation, body fat regulation, and leptin sensitivity. (More on this in the next post)
The general problem with the traditional approach is that eating less of the same food and exercising more clearly isn’t very effective for long-term weight loss. Many dietitians recommend to remove highly processed food and eat according to the food pyramid, but while this does lead to more weight loss compared to eating a diet based on ‘junk food’, it doesn’t really address the underlying problems.
Areas in the brain control the size of the body’s fat stores by regulating appetite, body heat production, metabolic rate, etc. While the approach to deliberately restrict calories and exercise more could be the way to go if you are already lean and want to shed more fat (e.g., down to single digits of body fat % for men), it’s not a sustainable approach for those that are overweight and obese. To permanently lose the weight we have to regain control of the system in our body that regulates fat storage. Only then can we unconsciously reduce food intake and turn our body into a fat burning powerhouse.