We all know that eating too much food, and particularly unhealthy food, is bad for us. At the same time so many people find it very difficult to stop. At the end of the day hunger is much more complicated than it might seem, and hunger is all about your brain. Most importantly learning how hunger is controlled by your brain can help you take back control!
Behind all your decision making there are physiological forces at work. Let’s take a look at how our brains drive food choices and how this leads to weight gain.
There are two types of hunger and associated eating:
Physiological hunger aka homeostatic eating – this is hunger and eating to provide our body the energy it needs and to stay in balance aka homeostasis.
Hedonic craving and eating – this is eating for pleasure or to deal with our emotional state
Most of the time we eat there is a contribution from both areas in that there are physiological mechanisms driving our hunger while at the same time we crave certain foods. There are many factors that drive hunger including but not limited to:
Our genetic background
Time of Day
Macronutrient Ratios of our meals
Hunger can be very complex and science is just starting to figure it out. What we do know a lot more about is why we stop eating. One reason is satiation – that feeling of being full from eating, and another reason is satiety (not the same thing!). Satiety is your feeling of satisfaction associated with a reduced interest in food.
When we eat there are two big physiological factors that tell us to stop eating:
Gastric Distension – which is your stomach telling your brain it is being stretched. This signal is sent to your brain via the vagus nerve which goes from your core to your brain. This is why eating higher fiber foods and foods with more bulk but less calories can help to control physiological hunger by signaling the brain through the distension of the stomach.
Hormones – when you eat your gut communicates with your brain using hormones including:
Cholecystokinin or CCK for short – when you consume protein and fat your gut releases CCK (again through the vagus nerve) to tell your brain to stop eating.
GLP-1 and Amylin – GLP-1 simulates the production and release of insulin which is very important for hunger. It also slows down food moving from the stomach into the small intestine. Amylin is another hormone proven to help reduce food intake.
Insulin – is secreted in response to protein and non-fiber carbohydrates including all sugars and starches but not by fat. When the body is in proper balance it also tells us to stop eating. HOWEVER, if we do not exercise at all and overeat (particularly if our diet is very high in sugar and starches and low in fiber) our cells become resistant to insulin. This can snowball into full-blow Adult Onset Diabetes with serious health consequences.
Leptin – helps manage your long-term energy and nutrient needs through a feedback loop. Leptin is released by fat tissue and how much excess energy (in the form of fat) we have stored. The more bodyfat we have the more leptin that gets dumped into our blood.
When things work properly and leptin signals go up, it signals the brain that we have plenty of energy and brings hunger down. Conversely as fat stores get lower (particularly if they get very low) the lack of leptin tells the brain we need to eat.
The brain also responds to lower leptin levels by limiting our movement. We literally move less – we tend to sit instead of stand and stop fidgeting. The couch calls to us! So we burn fewer calories through activity and our metabolic rate slows down through a process called metabolic adaptation. This is what allowed humans to survive long periods with low food intake and periods of famine.
The leptin feedback loop works well for most people, but there are genetic differences in how our body secretes and responds to Leptin. In addition, the food choices we make can seriously derail this important control mechanism!
Super palatable foods that are heavily processed can overwhelm the leptin feedback loop resulting in a lot of overeating. This includes foods with high levels of sugar, salt, and certain additives such as MSG which are hyper-stimulating to our entire digestive system. If these are the foods you eat regularly, your brain can become resistant to Leptin much in the same way that too much sugar and starch and no activity can make your cells resistant to the effects of insulin.
There are also certain foods that a generate a strong reward response in the brain such as coffee and alcoholic beverages. While we initially may hate the taste of these items, our brains learn to crave them which can completely disrupt the leptin and insulin feedback loops that normally work to control our appetite.
So What Should You Do?
The take home message is that super tasty and super rewarding foods are a dangerous combination! These types of foods are not found in nature and are a product of our modern food industry and culture. By making foods salty, sweet, starch and fatty then adding in special flavors and scents food companies are designing foods to make us overeat.
At the end of the day you have to cut these foods out and go through a short-period of withdrawal to allow your body’s innate regulatory mechanisms to kick back into place.
By making proper food choice and exercising we can gain a high level of control of these physiological mechanisms and our physiological hunger. Here at the keys:
Eat more whole, fresh, unprocessed foods such as lean meat, poultry, fish, eggs, and dairy.
Eat more fruits and vegetables! Strive for at least 5 servings per day!
Eat more slow digesting, high fiber foods such as whole grains, potatoes and yams, beans, asparagus, broccoli, etc.
Eat more nuts, seeds, avocados, coconut, and fatty fish for your fats.
Eat slowly and mindfully to give you brain time to get the right messages from your gut.
Eat less processed foods
If you stick to these food choices for a month or more you will start to notice your hunger and craving for certain unhealthy foods starts to go down as your body’s regulatory processes get back on track!