If instead you’re regularly struggling with moves or workouts that once felt easy, low energy may be the culprit, Heather Caplan, RD, a registered dietitian, running coach, and co-founder of the Lane 9 Project, tells SELF.
5. And you drag much more than usual afterward.
Yes, hard efforts—think long runs during half or full marathon training—can leave you feeling fatigued. But if you’re ramping up appropriately and fueling properly, you shouldn’t have to crash on the couch the entire rest of the weekend, Samuel says.
“You should be able to finish your long run—and, yeah, sure, be a little tired, but go do stuff with your kids, go run errands, go do what you have to do without feeling like you’re going to fall down,” she says.
6. In fact, you’d rather just bail on the gym altogether.
Regardless of your fitness goals—whether you’re preparing for a big event or working out for stress relief and well-being—it’s normal to feel ebbs and flows in motivation, McConville says. Even the most elite athletes have days when they’d rather not train.
But one sign of underfueling is an unexplained drop in your desire to work out or move, she says. So take note if sessions that once seemed fun to you suddenly lose their appeal, or you’re feeling tempted to skip out entirely more days than not.
“Tune into what your thoughts are saying,” Roth-Goldberg says. “If it’s a constant, ‘This feels so hard. This sucks. Why am I doing this? This is not fun.’ That is a sign of low energy.”
7. Your sleep sucks.
Although being undernourished leads to fatigue, you might struggle to fall asleep, or when you do nod off, you might find your shuteye constantly disrupted. Episodes of low blood sugar can cause you to wake up feeling anxious in the middle of the night, McConville says. Your sleep quality also suffers, adding to the feeling of dragging; you might be exhausted even though you think you’re sleeping enough.
8. Your gut rumbles way more than it used to.
Underfueling can hamper the way your digestive system works and disrupt your gut bacteria, causing symptoms that include diarrhea, abdominal pain, constipation, and bloating. The experience can resemble irritable bowel syndrome (IBS), McConville says.
This, too, can kick off a harmful cycle. One common reaction to those unpleasant GI symptoms is to avoid particular foods or food groups, such as dairy or gluten, McConville says. But if you start cutting those items out without adding in other sources of nutrients, your energy levels can drop further, digging you deeper into a hole.
9. Meanwhile, your hormones and vitamin levels are all out of whack.
Bloodwork you get at the doctor may also show abnormalities of certain vitamins and minerals. “We get micronutrients from food, and if there’s a shortage of food, you’re going to have a shortage of micronutrients,” Samuel says. And merely popping a multi won’t correct the issue, because underfueling also decreases the absorption of key nutrients.
