What it really means if you’re suffering from ‘carb flu’

Why depriving your body of carbs is more harmful than you think

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Feeling foggy, exhausted and inexplicably cranky with a side of headaches?

If you’ve been avoiding pizza and pasta like the plague (and you’re certain you’re not hungover), you might be suffering from ‘carb flu’.

Less gender specific than its slightly sexist cousin, ‘man flu’, the lesser known ‘carb flu’ refers to a week long period of illness induced by cutting carbohydrates from your diet.

Often experienced by those who embark on the Paleo diet – whereby all simple carbohydrates such as grains and potatoes are completely off limits – ‘carb flu’ is used to describe your body’s initial knee jerk reaction to the sudden abhorrence of carbs, which, despite leaving you feeling lethargic, sore and generally unwell, is to be expected when first starting the diet, according to Paleo Leap.

"When we restrict carbohydrates in our diet our bodies must adapt to a different way of producing energy from food, referred to as ‘keto-adaptation’ (keto- from ‘ketones’ – compounds produced by the breakdown of fatty acids)," explains Dr Ashton Harper.

"This process may take a number of weeks and during this time you may experience ‘flu-like’ tiredness and early fatigue because your body won’t be able to produce energy from fat and protein as efficiently as it can with carbohydrates," the medical advisor for probiotic brand, Bio-Kult told The Independent.

Advocates for the Paleo diet - which has more than 10 million posts under the hashtag on Instagram - claim that symptoms will subside once your body adapts to the dietary changes.

However, experts have been quick to point out that the newly-dubbed illness is not a legitimate medical condition and can actually be a sign that your body isn’t getting the energy it needs.

“The brain’s first source of fuel is glucose,” explains Rhiannon Lambert. “When this is suddenly restricted (as it is in a carbohydrate-deficient diet), you can feel very tired and low in energy. Your seratonin is also affected by carbohydrate restriction, which explains the low mood when you give them up,” the leading Harley Street nutritionist told The Independent.

The Paleo diet demonises most forms of carbohydrates, allowing little wiggle room for even the complex variety, which have been hailed by nutrition experts as an excellent source of fibre.

“Unrefined, low GI complex carbohydrates give you greater, longer-lasting energy and stable blood sugar because your body digests them more slowly,” explains Dr Marilyn Glenville.

“These come in the form of brown rice, oats, wholegrain breads and rye,” the leading nutritionist and author explained. However, none of these are included in Paleo.

Symptoms of ‘carb flu’ can come about from other diets too, explains Lambert.

“You can experience these symptoms on many diets which suddenly restrict energy intake. It is not healthy to make drastic changes like this to your diet overnight and this may have long-term health implications if not embarked upon with guidance and supervision,” she said.

Whilst some diets require participants to cut out entire food groups such as dairy and meat, Lambert stresses that this is by no means necessary, particularly if weight loss is the ultimate goal.

“I never advocate it,” she adds. “It is not sustainable; it can result in nutritional deficiencies and encourage a disordered relationship with food. Often most of weight lost on the scales with drastic diets is water weight or worse, muscle; it is not a sensible way to lose body fat,” she insists.