A Beginner's Guide to Low-Carb Diets

Eating a balanced diet that includes all three macronutrients ensures the body gets the necessary nutrients it needs to function well. When people areconsidering weight loss, limiting carbohydrates can help.^1-3

Many fad diets come and go, but low-carbohydrate diets seem to stick around. This may be because they deliver fast results. A low-carb diet for obesity management may work for some people.¹

What are carbohydrates and why do they matter?

Food is grouped into three types of macronutrients: proteins, fats, and carbohydrates (also called carbs). Carbs are found in grains, starchy vegetables like potatoes and corn, and fruits. There are two main kinds of carbs: simple and complex.^1,2

Simple carbs are sugars that are quickly digested. They provide a fast energy boost, which can cause a quick rise in blood sugar. Simple carbs are found in natural foods like lactose from milk or fructose from fruit. But they are also found in refined foods such as sucrose, or table sugar.²

Complex carbs break down into simple sugars during digestion, but they take longer to digest. Because of this, they tend to have a gentler effect on blood sugar and provide energy over a longer period of time compared to simple carbs. Complex carbs are found in:²

• Beans
• Lentils
• Nuts and seeds
• Barley
• Quinoa
• Whole grains, like oats, bread, and cereals
• Potatoes and sweet potatoes

What does "low-carb" actually mean?

A low-carb diet limits the amount of carbs you eat. There are many kinds of low-carb diets. Some diets limit the percentage of carbs within your total daily calorie intake. Others may limit the total amount of carbs eaten, usually in terms of grams.³

Here are some guidelines for understanding moderate-, low-, and very low-carb diets:³

• Moderate-carb: 26 to 44 percent of daily intake from carbs
• Low-carb: 26 percent or less of daily intake from carbs; or less than 130 grams per day
• Very low-carb: less than 10 percent of daily intake from carbs, or 20 to 50 grams per day

In comparison, American dietary guidelines recommend that 45 to 65 percent of your daily food intake come from carbs. Experts do not agree on what amount of carbs is okay to eat.¹

What can you eat on a low-carb diet?

People following this diet may eat:^2,4,5

• Proteins
• Fats
• Non-starchy vegetables

When eating a low-carb diet most of your energy will come from the other two macronutrients: proteins and fats. Protein options include:^2,4,5

• Meats, like chicken, fish, and grass-fed beef
• Eggs
• Lentils
• Beans
• Plant-based protein, like tofu and tempeh

When choosing fats to add to your diet, make sure they are nutrient-dense and not overly processed or fried. Good fat choices include:^2,4,5

• Butter
• Dairy products, likecheese, cottage cheese, and plain yogurt
• Nuts and seeds
• Olive oil and olives

Non-starchy vegetables can be eaten in a low-carb diet. These foods are a good source of fiber and vitamins. Options include (but are not limited to):⁴

• Artichokes
• Asparagus
• Beans
• Bean sprouts
• Beets
• Carrots
• Cauliflower
• Eggplant
• Greens
• Kale
• Onions
• Mushrooms
• Peas
• Tomatoes
• Zucchini

What should you limit or avoid?

Low-carb diets usually limit:²

• Bread
• Fruit
• Pasta
• Starchy vegetables (like corn and potatoes)
• Sweets
• Whole and refined grains

Can cutting carbs help with weight management?

Yes, cutting carbs can help. Research shows that low-carb diets can lead to rapid weight loss. In many people, water weight is shed first. But when someone sticks to a low-carb diet, fat loss follows.³

These diets can also help manage other health conditions, like type 2 diabetes largely by helping to stabilize blood sugar. Low-carb diets have also been found to lower triglyceride levels in some people., which may be a sign of an improved metabolism.³

What are the potential health risks to know about?

Yes, there are some health concerns worth knowing about. Some studies connect low-carb diets with a higher risk of heart disease. Specifically, studies have found some people experience an increase in low-density lipoprotein (LDL) cholesterol levels when following a low-carb diet. LDL is also known as the bad cholesterol.³

Researchers found a higher risk of death linked to a total daily intake of less than 40 percent carbs. However, the quality of foods eaten may matter most. One study followed two groups of people who ate a low-carb and low-fat diet: one group ate healthy, high-quality foods and the other ate unhealthy, low-quality foods. The study found a higher risk of death in the group that ate lower-quality foods.³

There may also be an increased risk of cancer when eating a diet high in animal protein.²

Some people may experience muscle cramps when they suddenly eat fewer carbs. They may also become constipated due to the decreased fiber intake. This is when someone has difficulty passing a bowel movement.²

People following very low-carb diets may also experience ketosis. Ketosis is a process that happens when your body starts to break down fat for energy. It can lead to:²

• Bad breath
• Headache
• Feeling tired or weak

How long should you follow a low-carb diet?

While low-carb diets can produce rapid initial weight loss, few studies support sticking to one for more than a year or two.²

In fact, there is little evidence to support the benefits of following a low-carb diet long-term. This is based on findings across many low-carb studies. The primary reason for weight loss on a low-carb diet is that people tend to eat fewer calories overall. This reduced calorie intake is likely due to increased protein and fat, which help you to feel fuller longer.²

Questions to ask your doctor before starting

Before starting a low-carb diet for obesity, talk with your healthcare provider. Some questions to ask them may include:

• Is this diet right for me?
• How long should I stick to this diet?
• How might this diet affect other health conditions I have?
• What are my personal benefits and risks of following a low-carb diet?