August 16 2017
This peach smoothie by Nutiva blends frozen peaches and Greek yogurt in a recipe that's perfect for summer.
It’s been hammered into our heads for years now: if we want to lose weight, we need to eat fewer calories and burn more of them through exercise. We’ve become so focused on creating this calorie deficit that we’ve forgotten what calories actually do: fuel our bodies. In an effort to maximize weight loss, many people (particularly women) eat as little as possible. And many of their trainers encourage this behavior, recommending women eat the fewest amount of calories their bodies need to survive.
But what about helping the body thrive? It may seem counterintuitive, but eating too little not only hinders your efforts at the gym, making it difficult to build strength and train effectively: under-eating can also prevent you from losing the weight you’re working so hard to banish.
Despite the prevailing myth that weight loss boils down to a simple calories in–calories out formula, a variety of lifestyle factors and their ensuing hormonal responses affect the ways our bodies respond to exercise and food. Reducing your caloric intake by a few hundred calories each day can indeed lead to sustainable weight loss, but reducing it significantly and forcing your body to function on the bare minimum it needs to survive triggers a series of changes in the body, all aimed at preserving energy in a perceived time of famine.
Your body responds to extreme caloric restriction by doing whatever it can to ensure your survival, mostly by conserving energy and putting calories toward its most basic functions. To do this, the body resorts to burning fewer calories. The result? Your body holds on to fat no matter how much you exercise or how little you eat. What’s more, while in this survival mode your body produces more of the stress hormone cortisol, which not only contributes to unhealthy belly fat but leads to leptin and insulin resistance, two hormones essential for regulating hunger, metabolism and fat storage.
This impacts your training in several ways. When the body feels it must prioritize essential functions (like regulating breathing, body temperature and blood pressure), it doesn’t feel that it’s safe to put resources toward things like rebuilding muscle tissue, which is the process that enables us to grow stronger. Training sessions therefore become harder when we’re underfed. Though we may feel like we’re performing with all we’ve got, we’re actually working at a severe energy disadvantage.
Without enough fuel, we can’t perform at our best. For weight lifters, this equates to an inability to lift at levels their bodies typically handle without any problem. In turn, this means they can’t create the necessary tears in muscle tissue that promote muscle growth and increase strength. For endurance athletes, it means they run out of gas more quickly while running or playing sports. Those microscopic muscle tears that all athletes generate need adequate fuel to heal. Even if you manage to push through a workout made difficult by a lack of fuel, your muscles can’t rebuild and your body may even resort to using the protein from your muscles themselves.
So how do you know if you’re eating enough for your activity level? The list below of common symptoms should give you a better idea.
Food is energy. As mentioned above, if you’re not eating enough calories, your body is going to use the ones it does have to support vital functions. This means there aren’t any left to do the things you love. If you’re dragging your feet at the gym every day, chances are you could benefit from more food.
Have you been working out like crazy but aren’t seeing results? Your body could be in starvation mode, fighting to preserve as many calories as it can.
If you’ve hit a ceiling in your weight training and haven’t seen an increase in months, it’s likely that you need to eat more, both to fuel your training and to repair your muscles.
Less than 5 percent of Americans consume enough fiber each day, despite generally eating more calories than necessary. If you are under-eating, the chances of your body getting enough fiber grow slimmer, which can easily lead to constipation. Another factor to consider is dehydration, which also contributes to slower bowels. Thirst is often mistaken for hunger, so if you’re trying to cut back on food, you may be ignoring your body’s signals for water in a misguided effort to stick to your diet.
Appropriate food intake allows for improved blood sugar control. The combination of consuming too few calories and over-exercising leaves your liver depleted of the glycogen stores it needs to keep your blood sugar stable, forcing your body to release stress hormones that eventually lead to the production of new glucose. When stress hormones are high, we have trouble falling–and staying–asleep.
Other common signs include constant hunger, irritability and mood swings, feeling cold all the time and experiencing irregular periods.
Unfortunately, it’s impossible to determine exactly how many calories your body needs, particularly since your energy expenditure varies every day. The general rule of thumb is that you need 10 calories for every pound of bodyweight. (For example, a 140-pound woman needs 1,400 calories on a sedentary day.) However, this baseline estimate doesn’t include the additional calories needed for exercise or for everyday activities like walking and doing chores. While there are many bodyweight calculators available that can tell you what your ideal weight (and thus ideal calorie intake) should be for your age, gender and height, both fail to consider things like frame size and muscle mass.
You can use these rules to get started, but listening to your body and looking for the above clues–hunger, fatigue, weight loss, fitness plateaus, etc.—will serve as much more reliable indicators of your needs.
So, are you eating enough?
About the author: Cortney Berling is a registered dietitian nutritionist at Tri-City Medical Center, a full-service, acute-care hospital located in Oceanside, California. She received her Bachelor of Science in Dietetics at The University of Cincinnati and completed her dietetic internship at The Cleveland Clinic. You can often find Cortney enjoying the San Diego weather where she spends most of her time running, playing beach volleyball, paddle boarding and hiking.