Who Should Not Go on a Low Carb Diet?

Max Carmody, MSc

Pregnant women, children under 18, and people with certain health conditions should not go on a low carb diet.

Carbohydrates are a type of macronutrient, they are one of the three primary ways that the body takes in energy. The other two are fat, and protein. Carbs are starches, fibers, and sugars that are found in grains, milk products, fruits and vegetables. Every day, carbs provide energy for the central nervous system and muscles. The digestive system breaks down carbs into glucose or blood sugar. The bloodstream absorbs the glucose and uses it as energy to fuel your body. There are different types of carbs, two of the main ones are simple carbs, and complex carbs. Simple carbs are broken down quickly for the body, and provide sudden spurts of energy. Complex carbs release energy more slowly.

A low carb diet, is essentially just a diet that is low in carbohydrates, compared to the other macronutrients, fat and protein. Typically low carb diets are any diet that has under 100 grams of carbs, although they can go as low as 50, or even 20 grams of carbs per day. Low carb diets generally make up for the lack of carbs by increasing the amounts of protein and fat consumed. There is no one single “correct” low carb diet, but rather there are a variety of different ones out there.

Potential Risks of Low Carb Diets

I love low carb diets myself, and have gone on them a couple of times. However, they do have their downsides. Some of the short term negative effects from low carb diets include headaches, constipation, or muscle cramps. Your brain may feel fuzzy, and you may experience more mood swings than usual. Especially the keto diet actually has a syndrome called “keto flu”. The keto diet is a form of extremely low carb, high fat diet that advocates eating less than 50, and as low as 20 grams of carbs per day. The keto flu is “a set of symptoms that many people who try the keto diet experience for a few days to a few weeks, including low energy, brain fog, painful headaches, mood swings, constipation, and nausea.” It is generally temporary, however. If you are experiencing symptoms like this, you can learn more about why low carb diets might make you tired, in this article that I wrote.

It is not completely clear what sort of long term risks low carb diets may pose. But restricting carbs for the long term may result in mineral or vitamin deficiencies and gastrointestinal disturbances. One recent study shows that people who significantly restricted carbohydrate intake increased mortality from common causes. Those who consumed the least amount of carbs were 50% more likely to die from cardiovascular reasons and 36% more at risk of death by cancer. It is important to keep in mind however, that this was just one study. If you would like to read some of the reasons why low carb diets can actually be a good diet if you do not fall in one of the groups of people who should not be on them, here is an article that I wrote on it.

Who Should Not be on a Low Carb Diet?

Low carb diets are especially not suitable for pregnant women. In fact, pregnancy is not the time for any sort of diet. Cutting back on certain food groups, or calories, will make it likely that the baby is not getting the nutrients that it needs. Dieting during pregnancy could even cause developmental delays, or a small fetus for gestational age. A pregnant woman should be eating a variety of fruits, vegetables, and whole grains.

A low carb diet is also not suitable for children under the age of 18. Growing children should be eating all of the food groups. This includes complex carbs, as well as lean protein and healthy fats. Growing children need the vitamins, minerals, and calcium that come from fruits, vegetables, milk and grains. A low carb diet will restrict these nutrients, and other important nutrients, that can affect growth and development.

Anybody who has been diagnosed with an eating disorder, or disordered eating, should avoid a low carb diet. A low carb diet, or any sort of restrictive eating, can be very triggering. Dieting excessively can cause a relapse, and people with eating disorders should only go on diets specifically ordered by dieticians. This includes people who suffer with binge eating. Restrictive eating is not the way to go for binge eaters, by feeling too restricted, it can cause worse binges than ever.

People with certain health conditions should not be going on low carb diets. One of these is type 1 Diabetes. It can be very dangerous for people with diabetes to have low blood sugar, and this can happen from taking insulin at the same time as severely restricting carbs in a diet. Gallbladder removal is another one. If you’ve had your gallbladder removed, your body will no longer have a reservoir for bile, which aids bile flow. If you do very low carb without boosting bile flow, you’ll feel terrible.

Those with thyroid disorders may not have to completely avoid low carb diets, especially after consulting a dietician or physician, but they should be careful about them. There is some evidence that a very low carb diet can suppress the Thyroid hormone T3. There is some research out there that very low carb diets may exacerbate fatigue and constipation in people with Multiple Sclerosis, although a very low carb diet may also be good for MS, but the research is lacking.

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