After eating what you thought was a huge, nutritious meal do you find yourself looking in the fridge?

Are you still hungry even after you've crammed yourself full of fibrous vegetables as has been so widely recommended?

Weirdly, it happens.

Hunger is a complex issue. Rather than simple addition and subtraction (calories in vs. calories out), hunger is more like a complex algebraic algorithm with the addition a lot of chemistry. Eating under your maintenance level of calories (which eventually is what is required for fat loss) will make you somewhat hungry. Along with this you are also fighting off psychological habits and triggers.

Vegetables & Satiety

I understand where the recommendation to fill up on vegetables comes from but it fails to work for many people. Hunger is way more complex than simply having a full stomach vs. an empty stomach. Mechanical hunger (having a truly empty stomach) is only part of the puzzle.

While eating a pound or two of green vegetables every day as some recommend will fill your stomach, it may not satisfy your appetite. This is because not all vegetables send your brain the "I'm full" signal.

Certain brain cells called tanycytes control appetite. These cells detect nutrients and inform your brain about the food you have eaten. These cells respond way better to abundant amino acids than to lettuce.

The amino acids arginine and lysine react strongly with tanycytes, which in turn release information to the appetite-controlling portion of your brain in as little as 30 seconds.

Foods with high concentrations of arginine and lysine include:

·       Sirloin steak

·       Chicken

·       Almonds

·       Mackerel

·       Avocados

Hunger Vs. Appetite

While the two terms are used somewhat interchangeably, hunger and appetite have very different meanings when it comes to science and nutrition.

Hunger is the urgent need for food due to lack of eating. It presents as a notable feeling of discomfort and is determined by the actual emptiness of the stomach. This feeling is the end result of a series of chain reactions due to a chemical signal sent from the stomach to the brain telling you it's time to eat.

Appetite, on the other hand is a desire to eat, usually after seeing, smelling, or thinking about food. Humans are capable of experiencing appetite regardless of how long it’s been since they last ate.

For many, appetite is associated with cravings and has little to do with dietary needs. It’s also the mechanism that tells your body to stop eating, even when you may still need to take in nutrition. This could, for example, occur when feeling ill or stressed.

Hunger can be measure in terms of the hormones leptin and ghrelin. Leptin is the hormone responsible for suppressing appetite, where ghrelin is responsible for increasing it.  While these two critical hormones have been identified and there is a basic understanding of how they play a role in generating hunger signals, it’s not clear exactly how these hormones function within the body and the exact responsibilities each plays.

Carbohydrates & Appetite

Studies have shown that those following a   feel less hungry and (more importantly) don't feel an increase in appetite, even as they reduce calories and lose weight.

While there is no conclusive research as to what causes this side effect, there are a number of theories.

Ketosis

Some researchers reason that the process of ketosis itself is the cause for decreased appetite on the keto diet. Both ketogenic dieters as well as those following other low energy diets have been identified as experiencing decreases in appetite. While the diets studied are very different from one another, they do both share elevated ketone levels. It is possible that a decrease in appetite hormones may stem from the process of ketosis itself.  

Protein Is the Most Satiating Macronutrient

The Standard Western Diet consists of 50% carbohydrates, 35% fat and 15% protein. A well formulated ketogenic diet recommends that 20%-30% of your calories come from protein.  Following the keto diet implies you are more likely to eat more protein than if you're following a standard high-carb diet. Protein is one of the most satiating nutrients, which may result in longer-lasting feelings of fullness and a decrease in appetite.

Glucose Concentrations

Studies comparing high fat and high carbohydrate breakfasts show a marked difference in blood glucose levels with a high carbohydrate breakfast causing them to spike and dip at much higher rates. The high carbohydrate breakfast eaters were also hungrier sooner.  This may indicate that an earlier rise and fall of glucose concentrations may increase hunger levels.

On a keto diet where carbs are even more scarce, blood sugar (glucose) spikes are practically non-existent. This would lead one to believe that a keto diet would further increase satiety levels. 

Not All Calories Are Equal

If you are following a dirty keto diet, this may not help. If, however, your keto food choices are predominantly whole, real foods, your food is likely to be less processed than a standard North American diet. 

The less processed food is the more energy your body will have to expend digesting it.  A great example is a scoop of nut butter which will require less energy to eat than if you ate those same number of nuts raw. 

Basically, eating more whole foods, makes it easier to attain and maintain a caloric deficit.

Whilst being aware of your caloric intake can have a positive benefit on weight loss, it is far from a perfect system and is rarely successful alone. If you changed your way of eating from processed food to whole foods you may notice a decrease in appetite. 

Cholecystokinin

The understanding of cholecystokinin and how it impacts satiety is still limited. Levels of cholecystokinin increase when partially digested fatty acids and protein hit your small intestine. This in turn facilitates the release of digestive enzymes and bile. 

Elevated levels of cholecystokinin may impact satiety. A diet higher in fat will deliver more fatty acids to the small intestine, releasing more cholecystokinin. 

Sleep & Appetite

Insufficient sleep is often the cause of mindless eating and consuming too many calories that go unregistered by your satiety signalling. Lack of sleep interferes with the reward centers of your brain and disrupts your internal body clock. This affects the regulation of leptin (the satiety hormone) and ghrelin (the hunger hormone). In short, bad sleep gives you cravings, usually for calorie and carbohydrate dense foods.

Keto Flu & Appetite

A keto diet can reduce your appetite but not your hunger, causing you to experience symptoms associated with starvation, yet still not feel the urge to eat. This is known as the keto flu.  Symptoms include light-headedness, fatigue, dizziness, headaches, cramping, decreased energy levels and irritability. To combat this focus on high quality fats, increase electrolytes and salt consumption, drink plenty of water, rest and ensure you are eating sufficient calories.

While many welcome the appetite-reducing effects of the keto diet, it can be a frightening experience. You may find your appetite will come and go as you progress through your keto journey. You may initially experience a dramatic increase in appetite as your body is burning through the last of its glucose and glycogen stores and is running on empty. The body sends hunger signals to the brain, asking to eat more food.

After the first few days of keto, your hunger levels may reverse, leaving you feeling less hungry than ever before. Some people struggle to reach their target calories for the day, feeling full after just a few bites. In this case you may want to consider drizzling a little extra healthy fat over your meals such as MCT oil or coconut oil. 

If you're struggling to eat, focus on eating whole foods and healthy fats. Avocados, coconut oil, MCT oil, fatty meats and fish, nuts, seeds and non-starchy vegetables. If the plate in front of you seems overwhelming, just eat what you feel comfortable with eating.

Eventually, the body adapts to a low carb high fat diet your energy and hunger levels should balance out. Most people still feel less hungry than they do while on a full-carb diet, but still feel full and satisfied and have sufficient energy to function and perform well.

If you continue experiencing drastic side effects of appetite suppression after several weeks on your keto diet it may be time to consult a physician or nutrition professional.

Bear In Mind

Appetite plays a large role in eating habits, diets, and weight loss. While it differs from hunger in many ways, appetite still affects how you feel about food, and often is the mechanism that gets you to eat.

Ketosis transforms the body in many different ways and really emphasizes how many different aspects of life are affected by the things you eat. The keto diet can disrupt hunger and appetite levels, which can be an unnerving experience. The important thing to remember is that every keto journey starts out with an imbalance, and then your body begins to slowly adjust and adapt to this new normal. From there, your ability to lose weight and address many of your wellness goals can change dramatically for the better.