Tofu is a vegetarian-friendly protein that is perfect for salads, sandwiches or even grilled on top of a pile of steamed veggies. While you’ll certainly get lots of protein and a slew of minerals from firm tofu -- calcium, magnesium, phosphorus, potassium and iron, to name a few -- you won’t get a lot of carbohydrates. Firm tofu is naturally very low in carbs, making it a perfect addition to a low-carb diet plan.
Firm tofu offers about 50 total calories from a 3-ounce portion, but only a small amount of those calories come from carbohydrates. That same 3-ounce slice of firm tofu has just 8 calories from carbs. If you’re counting grams instead, simply divide the calories from carbohydrates by 4, since carbs have 4 calories per gram. In this case, a serving of firm tofu has just 2 grams of carbohydrates.
Sugar, a simple carb, makes up roughly half of the carbohydrate content of tofu. While you may think that sugar is your sworn enemy, sugar from naturally occurring sources, including tofu, isn’t usually the issue. Tofu gives you a variety of nutrients for a relatively low amount of calories. Sugary treats on the other hand, offer a load of calories from sugar, but not a whole lot of nutrients. No matter the source, though, all sugars break down the same way in your gut. Sugars quickly convert into glucose in your small intestine, get absorbed directly into your bloodstream and then give you that almost instantaneous sugar rush feeling. But because tofu is very low in sugar, you're not likely to get that drastic surge of energy.
The other half of the carbohydrate grams are starch, a complex carbohydrate. Starch has all kinds of branches going in every direction, making it seem like a tangled mess. These branches are actually sugars, and during digestion your body has to work hard to break apart the sugars, eventually turning them into glucose. Since the transition time is much longer than simple sugar molecules, starch typically provides more of a long-term energy effect, not the quick burst you’ll get from sugars.
Carbs in the Diet
Between 45 and 65 percent of your calories should come from carbohydrates, according to the Dietary Guidelines for Americans 2010, but sugars and starches do not have separate recommendations. So, if you’re on a 1,600-calorie daily diet, you’ll need 720 to 1,040 calories from carbohydrates, or 180 to 260 grams of carbs. Those 2 grams of carbs you’ll get from a 3-ounce slice of firm tofu make up less than 1 percent of your carb allotment for the day, based on 1,600 calories.
Firm tofu has a trace amount of fiber too -- about 0.1 gram. While fiber is a type of carbohydrate, it doesn’t have any calories because it doesn’t transform into glucose like sugars and starches do. Fiber keeps its form, for the most part, as it travels through your bowels. Even though it doesn’t offer nourishment itself, fiber does help other nutrients absorb through intestinal walls and even pushes out indigestible waste. For a 1,600-calorie diet, you’ll need 22.5 grams of fiber each day based on the recommendation of 14 grams for every 1,000 calories in your diet, the Dietary Guidelines for Americans 2010 states.
Melodie Anne Coffman specializes in overall wellness, with particular interests in women's health and personal defense. She holds a master's degree in food science and human nutrition and is a certified instructor through the NRA. Coffman is pursuing her personal trainer certification in 2015.