Have you ever wondered what is going inside your body and brain when you have a specific craving? Who here has a sweet tooth? Ever get salt cravings? What about chocolate and fats? Well, in order to figure out what is going on inside your body, it is usually a good idea to look at the hormone involved, as hormones are the compounds which communicate to the brain what is going on in the body. These hormone signals don't "know" or care about weight loss, aerobic strength, fitness level, etc. They just "know" survival instinct and homeostasis - if something is lacking in your blood - glucose, sodium, iron, etc. - your body is going to do its best to get you to replace what is missing! This is often where cravings come from! However, you'll soon find what you crave is often NOT what your body needs!
Do You Have a Sweet Tooth?
Crave sugar? Sugar is the simplest form of energy, in fact all food gets converted into glucose which is transported to your brain and muscles for energy in the bloodstream. Glucose can come from ingesting simple carbohydrates which absorb in as little as 30 minutes from entering the mouth, from denser nutrients like fats and proteins which can take hours to absorb and through the process of gluconeogenesis are converted into glucose in the small intestine, or through the breakdown of stored energy sources - glycogen and fat. The hormones that control your blood sugar are insulin and glucagon, and if you have abnormal blood sugar levels, these hormones work in tandem to bring it back to normal. Insulin is released to help absorb carbohydrates and lower the blood sugar, while glucagon is the regulating hormone for absorption of protein, and helps raise blood sugar by releasing glucose molecules from stored glycogen.
When you crave sugar, you might be tempted to eat some gum drops or Swedish Fish! However remember, the reason you are craving sugar is that you need energy, and if you were to take in something sugary, the result will be a spike in the release of insulin, which will barely be able to keep up with the absorption of the sugar, and therefore whatever isn't used for energy immediately or stored as glycogen will be stored immediately as fat. Kind of like a Roman candle, you will get a quick spike of energy and then either crash and crave even more sugar. Therefore if you have a sugar craving, eat protein!! Why? Because this will have a short insulin spike, but then the insulin levels will lower and stabilize, the glucagon levels will raise as this protein is slowly converted into glucose and you will have sustained energy for a long period of time.
Are you always grabbing a salty snack?
Crave salt? Sodium is a mineral that is transported in the blood and must be kept in balance to control blood volume and blood pressure. If you have too much salt in the bloodstream, you will retain water to keep homeostasis. Likewise, if you overhydrate, you will urinate, clear in color, to remove excess water to, again, preserve homeostasis. Has this ever happened to you? You remembered to hydrate and so you drank a whole quart of water in one setting and then you had to go to the bathroom very soon after? This is a sign that your body cannot absorb the water fast enough, and therefore it must release the water through the urine. In order to hydrate properly, you must drink consistently in smaller portions throughout the day, not all at once.
If you crave salt, it is most likely an anti-diuretic hormone that is communicating with the brain trying to preserve homeostasis. Anti-diuretic hormone tells the body to retain water when dehydrated. If you crave salt, you might actually be dehydrated! So before you reach for the bag of Lays, drink a glass of water!
If you crave that Hershey bar, you most likely have a craving for fats. The hormone that regulates the absorption of fat is leptin, a hormone which also has a good deal to do with regulating appetite in general. If leptin is actively "talking" to the brain, it is most likely that your body is low on the stored form of carbs, glycogen, which can not only lead to low energy levels, but depression and irritability. Anyone who has ever gone through a first stage of an Atkins or South Beach type low-carb/no-carb diet knows that feeling of irritability! When your body is low on glycogen, it craves both fats and simple sugar and serotonin levels in the brain are altered which is most likely the cause of irritability and unhappiness. A Hershey bar is basically a sugar infused fat, so it is no wonder that is the first thing we want!
However, if to replenish glycogen levels, don't grab the chocolate bar, rather grab the quality carbohydrates (fruits, vegetables, whole grains) and quality proteins! This will suppress your fat tooth, and most likely you'll be easier to get along with for the rest of the day!
Why am I even HUNGRIER after a day of "bad" eating?
Ever notice that after a "cheat" day, Thanksgiving, or something similar, you wake up the next day and are hungrier than ever? This is because of the hormone Ghrelin. Ghrelin regulates the expansion and contraction of the stomach, and hunger. Imagine this - you pigged out and now your stomach had to expand to a bigger size than usual. The Ghrelin hormone now thinks this is "normal" size and will only reduce the size of the stomach slightly the next day. Then you pig out again because your body is telling you to eat more with a larger stomach, and again, the Ghrelin thinks this is the new normal, and when it contracts the stomach, you will again have a "bigger" stomach than you did even the day before.
If you know this is happening to you, the best thing is to just face the hunger head on and do your best to control yourself. Then your stomach will shrink back to its "original" size and you won't crave as much. Knowing this, I'd advise against full out "cheat" days, but rather if you need a cheat for reward, consider a cheat meal where you don't go crazy, but simply enjoy your food without overeating.
Of course this hormone plays an inverse role for people with eating disorders - the stomach shrinks so small that you are no longer hungry and your body is in starvation mode, using it's own muscle and fat stores for energy.
So, as you can see, often when you crave something, you have to eat the OPPOSITE to satisfy your body. Crave sugar? Eat protein. Crave salt? Drink water. Crave fat? Eat quality carbs and protein. Hungry? Why wait? No just kidding. Hungry (after a cheat day)? WAIT!