Dear Drs.: Yesterday, I went to lunch with a colleague and she’s following the keto diet. She claims she’s able to consume just 35 grams of carbs every day. Her candy bar’s label stated that it contained 26 grams of carbs that’s close to her carb allowance. She said it contained six net carbs. What do you think that means?
Dear Reader: If you aren’t aware, the goal of a keto, also known as ketogenic diet is to drastically restrict the amount of carbs consumed every day. The body uses the carbohydrates consumed as fuel. They are converted into glucose to meet immediate energy requirements. It also stores excess glucose within the body as glycogen. The convenience and speed of using carbohydrates to fuel your body is why they are the preferred source of energy. If you’re not getting enough carbs, the body will begin to use fat to fuel itself. This is a biological process known as ketogenesis. It’s not as effective as the use of carbs, and the body uses it for later as an alternative plan B.
The ideal threshold to reach and maintain ketogenesis lies around 50 or less grams of carbohydrate daily. The metabolism of every person is differently and some are forced to limit their intake even more than that. For a reference point to see how these limits impact your diet an apple of a medium size has 25 grams of carbs. The same is true for an Oreo cookie. It’s not too surprising, given the increasing popularity of the keto diet that a new industry of food has come into existence. It’s devoted to catering to those who need to cut down on carbs while still satisfying cravings for high-carb foods.
That (finally) brings us to net carbs as well as the candy bar that your loved with your friend. Net carbs is the sum of total carbohydrates present in the food, less any fiber. Let’s take the medium-sized apple that we talked about earlier. It’s got approximately 25 grams of carbs and around 4.5 grams of fiber. Take out the fiber and you’ll be left with 21.5 net carbohydrates. It’s thought that since fiber isn’t a significant factor in sugar levels in the blood the grams of carbs they represent can be overlooked.
Another type of carbohydrate which gets an exemption from net carbs is referred to by the name sugar alcohols. Although some of their structure are similar to alcohol and sugar but they’re not. They are actually a kind of carbohydrate that creates the sensation of sweetness. Because they don’t exert a significant impact on blood sugar levels, they are deducted from the total amount of carbs. This is how, after sugar alcohols and fiber content are taken into account that the 24 grams of carbohydrates that your friend’s candy bar contained have been reduced to six net carbs.
It’s important to be aware that the FDA doesn’t agree with net carbs as a concept. While the concept of counting net carbs can broaden the choices for food items of someone who is trying to limit carbohydrates or sugars, it could be a good excuse to add snacks and sweets to your diet. Net carbs aren’t a precise formula. Instead of accepting this unclear science, we suggest people who are conscious of their carbs to make sure they are eating whole food items that are naturally rich in sugar and fiber, and are low in sugar.
Eve Glazier, M.D., MBA, is an internist and associate professor of medicine at UCLA Health. Elizabeth Ko, M.D. is an internist and associate professor of medicine in the department of medicine at UCLA Health. Send your questions to askthedoctors@mednet.ucla.edu, or write: Ask the Doctors, c/o UCLA Health Sciences Media Relations, 10960 Wilshire Blvd., Suite 1955, Los Angeles, CA, 90024. Due to the sheer amount of mail received personal replies are not given.
