When we’re hungry we crave food and that’s pretty normal. When we’re not hungry and we still crave food, we have a problem, and when we crave foods that our bodies aren’t designed to eat we have an even bigger problem. The types of foods we crave, the timing, and intensity of those cravings all depend on the types of foods we are used to eating.
What We Crave
It is perfectly normal to crave carbohydrates to some degree. After all, our brains need some glucose to function. A healthy adult needs around 150 grams of glucose to fuel the brain. (Although, we can get on just fine without actually eating that glucose as our livers are equipped to convert at least that much protein into glucose through a process called gluconeogenesis, if given enough protein to make the conversion.)
We also crave fat. The body’s two options for fuel are fat and carbohydrate. Fat is an efficient energy source as it provides a high level of satiety and is important for healthy hormone balance. Additionally, while carbohydrate weighs in at 4kcal/g, fat weighs in at 9kcal/g. Clearly fat will carry us further for less, a fact of which our ancestors were keenly aware. Anybody hunting and gathering every day would surely choose the easiest path to satiety. Hence, they would choose fat.
Our bodies are fantastic at utilizing fat as energy. This is such an efficient type of fuel that we’ve been eating it since we were born. Medium chain fatty acids are found in breast milk (there is also a high concentration of them in coconut oil which makes a great endurance food).
Not only is a high fat meal what we were born eating but fat is such a fulfilling and easy source of energy that we spend the rest of our lives seeking it and eating it in quantity. Each one of us eats ample fat right from the beginning of our lives. This requirement does not change as we get older. We have evolved to to eat a diet high in fat as JS at Gnolls.org succinctly details in his article Why Humans Crave Fat. It’s just our evolution.
But our natural inclination towards fat cravings can get skewed in the Western world. That’s not to say that we stop craving fat. We don’t. But our carbohydrate cravings can be just as intense, if not more so.
Protein isn’t a food we generally crave apart from a small daily need. Apart from the 200 or so possible converted grams of glucose that your liver can convert in a given day, protein is not used for energy. Protein is used for cell repair and signaling, immune responses, and other processes, but not really for energy.
Six Causes of Food Cravings
1. Fat Restriction and Calorie Restriction
We are genetically pre-disposed to crave fat when we’re hungry. But most people these days have fallen prey to the Fat Hypothesis and restrict fat out of fear of high cholesterol and heart disease.
But, if you’ve already given up grains, sugar, and dairy, chances are you’re also limiting carbohydrates.
So you’re limiting fat and you’re limiting carbs – your only two available fuel sources? That is going to leave you pretty unsatisfied!
When you find yourself caving into cravings, it may just be your body’s way of saying, “I’m hungry”!
Junk food cravings might simply be calorie cravings in disguise.
2. Brain Chemistry: Endorphins, Serotonin, and Tryptophan
High glycemic foods such as breads and candy boost the brain’s production of endorphins and serotonin (temporarily, and then leave you drained). These neurotransmitters provide a sort of high that we get addicted to like drugs.
Endorphins are the body’s natural morphine and make us feel really good. High glycemic foods cause the release of endorphins.
Serotonin is another feel good chemical produced by the brain but many people have an impaired ability to produce it. The body can compensate for this lack by eating high glycemic foods to boost availability of tryptophan which can then be used to produce serotonin.
These neurotransmitter addictions are actually on par with cocaine addiction. You are addicted to a drug!
Additionally, our bodies react to a high glycemic meal by the release of insulin which causes the body to release excess ghrelin. Ghrelin is the hormone that makes us feel hungry. An excess of ghrelin results in fierce cravings for more food even after we’re already full.
A high carbohydrate diet is also responsible for leptin resistance due to the production of too much of it over time. Leptin is the hormone responsible for regulating our appetite. When leptin receptors are unresponsive, our desire for food remains active.
3. Imbalance of Intestinal Flora
If either yeasts or bacteria in our guts are out of balance, food cravings will ensue. Our guts contain literally trillions of microbes like bacteria and yeasts. Some of them are good and some of them are bad. When the bad ones start to gain turf and the good ones die off, all sorts of problems will start to surface, from headaches and fatigue, to irritability, to cravings and obesity.
Over the last decade or so researchers are beginning to understand that the human being has a symbiotic relationship with these microbes and that without them we become more susceptible to modern disease.
Jeffery Gordon, Director of Washington University’s Center for Genome Sciences, and his team have shown that normal weight people have more of a family of bacteria called bacteroidetes in their stomach and intestines, while obese people have more firmicutes bacteria.
His team was able to prove that there is actually connection to gut microbes contributing to obesity by “transplanting the gut microbiota from normal mice into germ-free recipients.” This increased “their body fat without any increase in food consumption.”
The reason for this might be that the bacteria are actually responsible for the amount of calories absorbed. The bad bacteria may somehow cause us to absorb more calories from our food. This means that two people could actually eat the same number of calories but the person with more of the bad bacteria will absorb more of those calories.
Additionally, gut bacteria has also been shown to be partly responsible for inflammation, which we already know contributes to obesity. According to Chris Kresser, “different species of bacteria seem to have different effects on appetite and metabolism.” Studies suggest that certain strains of bacteria are actually responsible for the systemic inflammation which leads to obesity.
Rebuilding gut flora is essential for human health but it isn’t always easy in our modern world where humans are driving many of these necessary microbes to extinction through our sterile and toxic diets and lifestyles. By reducing toxic exposure, eliminating refined sugar, eliminating sterile packaged foods, by including a variety of probiotics, by getting our hands dirty in out nature, and never using an anti-bacterial soap again, we can start to rebuild what we have lost and get healthy again.
It takes time to repair the amount of damage that us Americans manage to do to ourselves. Adding antimicrobial supplements like coconut oil and fermented foods and probiotics like apple cider vinegar we can help speed up the process.
4. Bad Moods
Calorie restriction has been proven to cause irritability, hostility, and depression (unless your’re efficiently utilizing your fat stores, which you’re not doing if you’re still eating a diet high in carbohydrates). Elevated insulin leads to hypoglycemia which also causes irritability. Withdrawal from brain chemicals is akin to drug withdrawal and causes a host of mood disorders.
Mood disorders often lead to emotional eating. When we get depressed, we eat more in attempt to alleviate the pain. When we’re depressed it’s harder to fight urges because we just don’t care about the consequences. Elevating the mood is paramount in preventing the mindless eating of junk food.
Improving ones mood has other advantages. Positive moods improve ones willingness to make positive changes and the strength it takes to fight hunger and persevere through the challenge of transition.
5. Gluten and Food Allergies
Melissa Diane Smith goes into the games certain food chemicals play on our minds in Going Against the Grain. Reaction to gluten is not just a problem for celiacs but quite possibly for most people these days.
Eating wheat (or any other foods which causes the immune system to produce antibodies) causes tissue damage and can cause or exacerbate myriad health complications including, but not limited to, migraine, joint pain, depression, fatigue, hypoglycemia (which leads to overeating), and even schizophrenia. Gluten itself can cause a release of insulin and a suppression of leptin which will also contribute to cravings.
6. Excess Fiber
It’s common to start eating tons of vegetables after switching to the paleo diet. We’re indoctrinated with the idea early on that vegetables are good and meat is bad.
Fiber related disorders are a topic about which most of us are unaware. It’s a pretty simple (albeit boring) fix to an almost debilitating (in some situations) compulsion to eat. The most comprehensive research I’ve seen on the subject can be found on the The Fiber Menace website. This is some pretty amazing material worth checking out.
7. Fructose Malabsorption
Fructose is a sugar found in fruits and some vegetables. When someone does not digest fructose, it passes through the digestive system undigested, causing cravings, mood problems, bloating and other symptoms. FM is a common cause of severe food cravings. Read more about it here.