Imagine you are out to dinner with a friend and the bread arrives at your table. You are not very hungry, but you think, "l'll just have one little piece." A few minutes later, you realize you have eaten three slices before your meal even arrives. What's going on here?
Even though you are not physically hungry, your body gave you the signal to eat. That's the work of three hormones in your body that control hunger -- insulin, ghrelin and leptin. They are important because the way these balance can impact your weight and health.
Insulin is made in the pancreas and allows cells to take sugar or glucose from the blood stream to use as energy.
Approximately one-third of the population inherits a resistance to respond properly to insulin, which prompts the pancreas to secrete more insulin if you eat a meal high in refined or "simple" carbohydrates such as white pasta or white bread.
When the insulin does not respond normally -- allowing sugars to enter the cells of the body -- you can experience insulin resistant hunger. Rather than being physically hungry, you might experience it as a "gnawing" desire to eat.
If you consume meals high in refined carbohydrates on a regular basis, that are not balanced with respect to protein and good fat, you may continually crave carbohydrates.
Think back to the restaurant example with the bread, or perhaps a recent party where you have helped yourself to a few chips, only to find that you ate a good portion of the bowl. Again, even though you were not physically hungry, your body gave you the signal to eat.
In these situations, you know what you are "supposed" to be eating, but your body continues to give you the signal to eat more carbohydrates.
Running on Empty
The more refined carbohydrates you consume, the more your energy levels fluctuate between high and low throughout the day. Consequently, you never truly feel like you are running on real energy.
Not to mention, your body isn't a good ally here. It prefers carbohydrates or glucose as its primary fuel. If you are eating a very high carbohydrate diet, your body will first try to utilize the carbohydrate before tapping into calories from fat or protein.
To make matters worse, you may not tap into your fat stores if you are trying to lose weight. If you continue to a diet high in sugar or simple carbohydrates, your body will prompt you to continue eating these foods, leading to increased hunger and chronic carbohydrate cravings.
Ghrelin Grows and Leptin Lowers
This first thing to know is that ghrelin makes you feel hungry and leptin causes you to feel full. An easy way to distinguish between the two is that ghrelin grows your appetite and leptin lowers it.
They work to your advantage when your diet is in balance and you are receiving adequate sleep. They work to your detriment when your diet is out of balance and you are lacking sleep. Most importantly, the macronutrients you eat -- carbohydrate, protein and fat -- strongly influence them.
Appetite Ups and Downs
David Cummings, M.D., of the University of Washington School of Medicine, has done multiple studies on how macronutrients affect the hunger hormones.
In 2007, he and his colleagues conducted a study that found:
• Proteins were the best suppressors of appetite
• Fats have a neutral affect on appetite
• Carbohydrates initially lowered the appetite, but then rebounded soon afterward with a vengeance -- causing the appetite to be even greater than before the food was introduced.
Sleep and Appetite
In 2004, Eve Van Cauter of the University of Chicago conducted a study to see if sleep deprivation altered appetite. They tested men who slept 4 hours for two consecutive nights followed by 10 hours of sleep for two consecutive nights. They found that after sleeping for 4 hours versus the 10, the men had:
In summary, sleep deprivation not only increases hunger levels, but lowers metabolism, not a good combination for health and weight loss.
How to help your hunger hormones work to your advantage:
1. Have protein at all meals, but especially at breakfast. Breakfast sets the appetite tone for the day so consuming some high-quality protein such as eggs, organic plain yogurt or cottage cheese with some nuts will lower your ghrelin levels and minimize a spike in insulin levels to keep hunger at an even keel throughout the day.
2. Stay away from refined-carbohydrate-only meals and snacks such as cereal, a bowl of pasta, crackers, chips and starchy snacks. Even having a healthy snack such as fruit alone can trigger a spike and a drop in insulin, so add some nuts or a piece of cheese with the fruit.
3. Put ghrelin to rest: Getting adequate rest keeps your ghrelin and leptin levels in check to allow for normal levels of hunger.
Susan is the author of A Recipe for Life by the Doctor's Dietitian. For more information, visit susandopart.com
Follow Susan B. Dopart, M.S., R.D. on Twitter: www.twitter.com/smnutritionist