Balancing Huger and Satietyby Amylee Amos PhD, RDN, IFMCPNutrition
To snack or not to snack, that is the question that I hear all the time. It brings up another huge issue- how many meals should we eat per day? Three square meals? Lots of small meals throughout the day? The media seems to send us a different message every week. So what is the answer, and specifically what is the answer if your primary concern is brain health and preventing Alzheimer's disease?
As with everything in nutrition science, there isn’t one clear cut, black and white answer. Sigh, I know. The truth is, it depends. For many of my clients, their mental health thrives off of two meals a day with no snacks. For others, a few small snacks along with their meals helps them feels at their best. We take a number of factors into consideration when determining how a client plans meals and snacks throughout the day including genetics, metabolics, anthropometrics, and lifestyle.
We take all of that information and create a personalized meal and snack timing outline, including an optimized plan for time restricted fasting. But the really important part is what comes next: listening to your body. It’s powerful to have outlines and templates that structure your lifestyle, and when it comes to preventing Alzheimer’s disease, meal planning and timing is an essential part of that. But, equally important is realigning your body so that you can understand and respond to the signals it’s sending you. In theory, that’s how you should determine when and how to snack.
The issue is, many of us have lost the ability to distinguish between hunger and appetite. We almost use those two words interchangeably. But they are not the same thing. Hunger is a physiologic feeling of needing to eat- think a growling stomach or feeling fatigued from lack of food. For the most part, when we feel hungry, we should eat, regardless of our meal planning efforts. However, most of us eat whenever we have an appetite. Appetite is wanting to eat- think craving a donut after walking past the donut shop, or snacking on something just because it's in front of you. The two are distinctively different, and understanding that difference is key for maintaining brain and overall health.
When we eat because we are hungry and stop eating when we satiated, the body has the ability to maintain homeostasis, or balance and proper regulation. In fact, there are hormones produced by the body that help us do this: ghrelin, our hunger hormone, and leptin, our satiety hormone. These two hormones work together to help maintain energy balance. Ghrelin is a short-acting hormone produced when the stomach is empty, signaling a need for food. Thus, before eating ghrelin is elevated and after eating ghrelin is low. Alternatively, leptin is a long-acting hormone that signals the brain that you’re full. It is secreted by adipocytes or fat cells, and it tells the brain that you can stop eating. The more fat cells a person has, the more leptin they produce. This hormonal balance is designed to help the body regulate intake of food, and in theory helps a person avoid too little or too much food intake (1).
The issue is this harmonious balance gets thrown out of whack. This is often referred to as leptin resistance. This happens when the body has excess fat cells, which are making excess leptin, and the brain resists leptin's message (2). This creates a vicious cycle of increasing fat cells, increasing leptin, with no increase in satiety. Leptin resistance makes weight loss challenging, but this can be a problem regardless of weight. It disrupts our ability to listen to our body’s signals- and as we’ve mentioned, tuning into your body and making the decision to have a meal or snack based your level of hunger is the best guide for eating.
So, why does this happen? Well, our good ol' standard American diet and sedentary lifestyle have left us out of touch with the feeling of hunger, and cause imbalance in satiety and hunger hormones that control these feelings. The saturation of our diet with high fructose corn syrup has been documented to exacerbate this issue (3). But the good news is, you can rebalance this system and get back in touch with hunger versus appetite and satiety cues.
To start making an effort to rebalance this system, try to check in with your body prior to snacking. Take a moment to consider why you are going to eat. Are you watching someone else eat? Are you bored? Are you anxious? Has something triggered your desire for food? If you answered yes to any of those questions, maybe reconsider your snack. If you answered no, and your self check-in determined that you are indeed hungry, then opt for a brain boosting snack, made up of whole foods.
Beyond practicing mindfulness before eating, engage in regular physical activity, work on stress management, and get adequate, restorative sleep to help stabilize your appetite, hunger, and satiety. Specifically, impaired sleep and imbalanced circadian rhythms has been shown to increase ghrelin and decrease leptin level (4), which can probably account for why people make poorer nutrition decisions when they are tired.
Now of course, there are exceptions to even this very basic rule of eating when we’re hungry. Extended fasts are extremely beneficial for carriers of the ApoE4 allele. Many of these people often feel hungry as they adjust to the fasts, but they do just that: adjust. When extended time restricted fasting like this is optimal based on genetics and overseen by a nutrition professional to ensure safety, it may be necessary to push past the hunger until your body has adjusted to the longer fasting time. It’s always important to check with your doctor or dietitian before starting up a fasting regimen such as this to make sure that it’s safe, but also that it will actually benefit you.
- Kock, M.D., Jakobsdottir, S., & Drent M.L. (2007). The role of leptin and ghrelin in the regulation of food intake and body weight in humans: a review. Obes. Rev., 8(1): 21-34.
- Woods, S.C. (2009). The control of food intake: behavioral versus molecular perspectives. Cell Metab. 9(6):489-98.
- Shapiro, A., Mu, W., Roncal, C., Cheng, K.Y., Johnson, R.J., & Scarpace, P.J. (2008). Fructose-induced leptin resistance exacerbates weight gain in response to subsequent high-fat feeding. Am. J. Physiol. Regul. Integr. Comp. Physiol., 295(5): 1370–1375.
- Spiegel, K., Tasali, E., Penev, P., & Cauter, E.V. (2004). Brief Communication: Sleep Curtailment in Healthy Young Men Is Associated with Decreased Leptin Levels, Elevated Ghrelin Levels, and Increased Hunger and Appetite. Ann Intern Med., 141:846–850.