Between a holiday cornucopia and food pushers, the holidays leave us fueled and replenished. But when the thick of joy recedes, the nefarious children of indulgence– bloating and food guilt– might claim your body. It is difficult to avoid overeating during the holiday season but an important question to ask is whether it’s something that must be avoided at all costs. Holidays are days when we are supposed to bond over nourishing food and drinks.
Excessive consumption of food at a fast pace may lead to pain and digestive problems. For this reason, you may want to slow down and watch what you eat. That said, concerns of weight gain don’t make the strongest case against holiday indulgence. It’s easy to think that any amount of food consumed north of our usual intake will be stored as fat. The morning following the night of feasting, you may step on a scale and bat an eye at [1] your new weight, thinking, “I knew it. I’ve gained three pounds.” Putting aside the valid question of whether three pounds matter at all, overeating for a couple days can’t do that much to your body. Most of the weight gained overnight is due to increased water retention, which will be discharged in a week.
Psychologically, it may feel as if everything that enters your body becomes a part of it. But there are so many factors that affect how food is processed: Total daily energy expenditure (TEE), starting body composition, the macronutrient composition of the surplus, and glycogen depletion state. TEE is the total amount of energy you spend in a day, which depends on your resting metabolic rate (RMR), the thermic effect of food and activity, and non-exercise activity thermogenesis (NEAT).
For the scope of our discussion, let’s focus on the thermic effect of food and NEAT. The thermic effect of food is the energy spent on digesting your food, while NEAT is the energy spent on any bodily activity, including fidgeting and walking around, that is not part of controlled training. So going to the gym won’t increase NEAT while walking from your car to your apartment will affect it. Interestingly enough, eating more food will increase the thermic effect of food and NEAT, and subsequently, increase TEE.
The macronutrient composition of the surplus, meaning the amount of fat, carbohydrate, and protein in the food, also affects how much fat you’ll gain after overeating. Compared to carbs, fat is more readily convertible to storage. A study found that in a very short window, fat overfeeding can cause acute accumulation of fat while carbohydrate overfeeding has less pronounced effects. This is because carbohydrate replenishes our glycogen stores and fuels cells before being converted into fat. (A cautionary note: in the long run, excess dietary carbohydrate leads to similar levels of fat accumulation as excess dietary fat).
The upshot [2] is that if you overeat for a couple days, your blood sugar level and water retention rate will instantly go up. Between three to ten days after the overfeeding window, your body will have restored balance (given that you go back to your usual diet) and gained several grams of fat. So treating yourself with one more piece of pie is not the end of the day. Instead, think about how your body can utilize the surplus and benefit from it!