3 dairy items that could screw up your keto diet

As any ketogenic dieter knows, the lifestyle requires a lot of diligence. Even snacking on a banana could ruin your diet.

The main goal of keto is to use fat instead of carbohydrates for energy, a process known as ketosis.

Generally, keto dieters eat lots of fat, a moderate amount of protein, and just 20-30 grams of carbohydrates per day to maintain ketosis. For context, that's about half a medium bagel.

Some foods, like bread, are known for their carby goodness, so it's no surprise they'll knock you out of ketosis. But there are plenty of foods that could unexpectedly throw your diet out of whack.

If you're trying to remain vigilant on the keto diet, double check the nutrition label for these six surprising sources of carbohydrates.

1) Milk

Milk is a great source of protein and fat, but 1 cup of 2 percent milk contains 13 grams of carbohydrates. Given that you're likely to eat other foods with carbs throughout the day - like vegetables or nuts - that glass of milk may put you over the recommended 30 grams of carbs per day.

2) Cottage Cheese

Low in fat and high in protein, cottage cheese has long been a staple for many dieters. However, people on the keto diet may want to be careful about eating cottage cheese in abundance. A single cup of small curd cottage cheese has roughly 8 grams of carbohydrates. Although it may be good to eat alone as a filling snack, be careful about pairing it with other foods that have traces of carbs, like avocados and nuts.

3) Yogurt

Yogurt topped with a few nuts might seem like a no-brainer keto snack, but a 5.3 ounce serving of plain yogurt has 12 grams of carbohydrates. If you opt for flavored yogurt, like vanilla, that carb count doubles to 24 grams of carbohydrates for 6 ounces. Your best bet is to choose plain Greek yogurt, which has as little as five grams of carbohydrates for a 7 ounce serving.