Human appetite is intricate and somewhat unpredictable—it is affected by hormones released by the brain, digestive system, glands, and fat cells. Many different variables may impact your hunger in this scenario. I often talk to hunters who prefer to keep moving instead of stopping to fuel. A rigorous hunt alone will dramatically increase caloric needs, and if that hunter is eating less than normal because of the hunt, they are left with a significant calorie gap. Here are some likely reasons your appetite has changed and why it is important:
Reason #1: Strenuous aerobic exercise blunts appetite. During acute high-intensity exercise or stress, the neurotransmitters norepinephrine and epinephrine are released. These prioritize the sympathetic "fight or flight" response in the body, and eating is put on hold. During this level of activity, research has also shown suppression of appetite-stimulating hormone ghrelin and increased levels of satiety-inducing hormones (1, 2). Solution: Your appetite should return within 15-30 minutes if it is being blunted by strenuous exercise. Drinks or easy-to-digest foods may be helpful ways to fuel during this period. Try smoothie packets, sports drinks, energy chews, or raisins. You can use periods of lower activity, such as glassing, to also grab a quick, energy-dense snack. Note: Hunting at high altitude can also have a blunting effect on appetite. This will be addressed in a later article.
Reason #2: The body alters hormone release while experiencing an energy shortage. During an energy shortage, ghrelin levels increase, while leptin, a satiety hormone, decreases. This interaction typically increases the motivation to eat. This study (3) found that ghrelin levels peak on day 1 or 2 of an energy shortage while exhibiting a small but significant decrease in peak ghrelin levels during subsequent days. This could, theoretically, negatively impact appetite during your hunt. Further complicating it, higher ghrelin levels do not necessarily mandate greater motivation to eat (4). This may be related to the higher levels of satiety hormones, as described in Reason #1. Solution: Fuel with energy-dense and nutritious foods during regular periods of the day. This will help prevent any need to try to catch up later. While in the field, your diet should have some fats and proteins. However, your diet should be heavy on carbohydrates when doing intense activity for extended periods of time.
Reason #3: The hunt is more interesting than food. The brain plays an integral role in appetite. This would be another time when increased ghrelin levels are not necessarily translated to increased hunger. It seems distraction may play a role in people ignoring and temporarily forgetting hunger (5). Solution: Experiment with foods in the off-season to find the ones you enjoy. Elk will always be more interesting than food, but if you get stuck in a rut with the food you pack, it is very unlikely you will eat enough.
Why does this matter? It all goes back to optimized fueling. Sure, you can pull from your fuel stores for a time, and sure, you could use this period of heightened activity as an opportunity to lose weight. I would argue from a sports nutrition standpoint that the hunt is not the time to do it. Athletes undergo strategic fitness and nutrition training that is periodized. Each phase of training has a need and goal in mind, whether weight loss, increased fat oxidation, altitude acclimation, or performance. Nutrition facilitates these goals and adaptations.
Exercise and caloric deficits boost cortisol levels in the body, inducing a catabolic response (6). In the proper context and in limited amounts, catabolism (the process of breaking down) is an important part of training (think muscle breakdown to lead to muscle growth). On a multiple day hunt, however, the catabolic response of exercise combined with inadequate fueling will impair muscle recovery, hiking intensity, and endurance.
Fuel like an athlete: come into hunting season ready and with a plan. Save weight loss and nutrition training for the off-season, and give your body the fuel it needs to allow for higher athletic performance.