Here are some of the most common side effects of slashing or eliminating carbs from your diet:
1. You frequently feel tired
Carbohydrates energise your body and fuel your muscles (it’s one reason we often crave carb-rich comfort food in winter as our bodies burn more energy to main their core temperature). So it follows that curbing your intake could leave you feeling sluggish.
Much of this has to do with how carbs are converted in the body. After being broken down into simple sugars, they are “absorbed into the bloodstream, where glucose becomes fuel for the body,” Clarissa explains. “Insulin helps cells take up glucose for energy or stores it as glycogen in the liver and muscles.
“When your carb intake is too low, glycogen stores are quickly depleted, leaving the body with less readily available energy,” she continues.
Cue your body has to work harder to convert energy from the protein and fats you consume, and weakness– dubbed “keto flu”— sets in.
2. Your workouts feel tougher
This also explains why you may feel weaker when working out as carbs fuel your muscles and muscle contractions.
“Another important benefit of carbs is that they help your body to preserve protein,” says Riya. “When you consume enough carbs, your body can use protein mainly for repairing and building muscle rather than relying on it for energy. This is crucial if you’re aiming for muscle growth or trying to stay fit.”
3. You’ve got brain fog
Carbs also fuel your brain. “When you eat carbs, your body breaks them down into glucose, which is what your brain uses to function properly,” says Riya. “The brain doesn’t have a way to store glucose, so it relies on a continuous supply of it through the bloodstream.
“If you’re not getting enough carbs, your body can struggle to supply the glucose your brain needs,” she continues. “Essentially, without enough energy from carbs, you might find it hard to concentrate, think clearly, or stay focused on tasks.”
In one study, women were divided into two groups: one group followed a strict low-carb diet, while the other group ate a balanced diet. Cognitive tests were taken at various points—before starting the diets and again after 48 hours, one week, two weeks and three weeks.
“The results showed that those on the low-carb diet didn’t perform as well on memory tasks compared to the balanced diet group,” Riya notes. “Interestingly, once they reintroduced carbs, their memory improved, showing just how important carbs are for brain function.”
4. You’re feeling bloated
“Many carbohydrate-rich foods, particularly whole grains, fruits and vegetables are high in fibre, which is essential for gut health,” says Clarissa. “When you reduce your carbohydrate intake, you often decrease your fibre consumption.
“Fibre plays a crucial role in promoting regular bowel movements, so without sufficient fibre, you may experience constipation. This backing up in the digestive system can result in gas and bloating.”
Another culprit may be low-carb or low-sugar alternatives. “These can sometimes have artificial sweeteners or sugar alcohols, which – if consumed in excess or by those with sensitive stomachs – can cause side effects such as bloating,” adds Clarissa.