Legumes & Beans: Health & Weight Loss Benefits

Beans and legumes are a high-protein, nutrient-dense, low fat, and low-glycemic index food. See how making legumes an eating habit can improve the quality of your diet and maximize your weight loss efforts.

Various legumes sorted into ceramic dishes

Many Americans are turning to plant-based foods for the bulk of their nutrition. It’s a smart choice. Diets rich in fruits, vegetables, seeds, whole grains, and nuts are associated with positive health outcomes. One component of a plant-based diet that is frequently overlooked in the United States is legumes.

Fewer than one in ten Americans report eating legumes such as beans, peas, and lentils on any given day<sup>1</sup>. Many countries have a rich indigenous tradition of consuming legumes as an essential staple. 

What Are Legumes?

Legumes (also referred to as pulses) are members of a large family of plants called Fabaceae<sup>2</sup>. The edible part of the plant is usually the fruit or the seed. 

If it’s a food that grows in a pod, chances are, it’s a legume.

Popular Types of Legumes

  • Red, green, and black beans
  • Peas
  • Lentils 
  • Fava beans
  • Chickpeas
  • Tamarind 
  • Soybeans
  • Peanuts

Nutritional Value of Legumes

  • High in protein
  • An excellent source of dietary fiber
  • Rich in B-vitamins
  • Rich in iron, calcium, magnesium, manganese, potassium, phosphorus, and zinc
  • Low in fat
  • Free of cholesterol
  • A source of complex carbohydrate
  • Contain no preservatives, additives, or stabilizers

One way to think about their nutritional composition is that they are similar to meat, but with less iron and no saturated fat. They are the protein that is also a vegetable.

Let’s take a closer look at a couple of favorites: lentils and black beans.

Black Beans
(1/2 cup)
Lentils
(1/2 cup)
Calories 114 150
Protein 8 grams 12 grams
Fat 0 grams 0.5 grams
Carbohydrates 20 grams 25 grams
Fiber 7 grams 4 grams
Sugar 0 grams 0 grams
Glycemic Index 30 (Low) 21 (Low)

Note that neither black beans or lentils are particularly low in total carbohydrates, but since they contain complex starches rather than simple sugars, their glycemic indexes are low. Studies have shown that patients with diabetes who regularly consume dry beans, peas, and lentils have greater reductions in hemoglobin A1C when compared to a diet high in whole wheat, as well as overall improved glucose and lipid metabolism <sup>3, 4</sup>.

In other words, legumes are a high-protein, high fiber, and low-glycemic index food. 

<p class="pro-tip">Related: 5 High-Fiber, Low-Glycemic Foods</p>

Glycemic Index and Glycemic Load of Legumes

When you eat a food that contains a carbohydrate, your blood sugar will rise. The amount of that rise is a function of the food’s glycemic index. The glycemic index is a rating system that was devised to compare the expected rise in blood sugar for a particular food to the rise seen after eating plain table sugar, which is assigned an index of 100. The glycemic load of a meal takes in account the glycemic index of a food plus the amount of that food (by weight) that is ingested.

<p class="pro-tip">Read more about glycemic index and glycemic load </p>

Legume Glycemic Index Glycemic Load
Black Beans 31 5
Kidney Beans 47 15
Red Lentils 31 5
Lima Beans 33 5
Chickpeas 33 5
Peanuts 23 1
Green Peas 9 1

What Are The Health Benefits of Eating Beans?

Weight Control

Data from the National Health and Nutrition Examination Survey (NHANES) shows that adults who regularly consume legumes have a lower body weight and a smaller waist size than non-consumers<sup>5</sup>.

Gut Health

There is some suggestion that oligosaccharides (the components of beans that cause gas) promote intestinal health and may help reduce colon cancer through their effect on gut bacteria<sup>6</sup>.

Heart Health 

A large epidemiological survey found that men who ate legumes four times per week had a 22% reduction in coronary heart disease than those who consumed them only once per week<sup>7</sup>.

Blood Pressure Reduction

A review of eight studies with over 500 participants found that exchanging legumes for other foods with the same caloric value significantly reduced systolic and mean arterial blood pressure<sup>8</sup>.

Diabetes and Metabolic Syndrome Management

Thanks to their low glycemic index and their beneficial effects related to weight control, beans are a healthy choice for those with diabetes and metabolic syndrome. Low fat, high fiber foods such as legumes and whole grains have been found to protect against the development of Type 2 diabetes<sup>9</sup>.

Cholesterol Management

Eating a non-soy legume diet helps reduce LDL and total cholesterol<sup>10</sup>.

Illustration of beans

How Often Should You Eat Legumes?

The Dietary Guidelines for Americans recommends eating 6 servings of legumes per week. One-half cup is considered one serving<sup>11</sup>. Few Americans meet this goal. The average intake is less than one cup per week<sup>12</sup>.

Cooking and Preparing Beans

Though some beans may take a little preparation (if you select the dry variety) you don’t have to be a gourmet chef to cook them in delicious ways. Put the beans to soak in water in a large bowl overnight. Soaking the beans helps them cook faster and helps reduce bloating. Draining the water a couple of times and refilling helps to reduce some of the gas-producing effects of beans. Due to their small size, lentils don’t need to be soaked.

Dry beans can be cooked in a pressure cooker, or a regular pot filled with water. Some chefs add a teaspoon of baking soda to shorten the preparation time, but this is optional. After bringing the pot to a boil, reduce to medium to low heat and allow to cook until soft (usually two more hours). 

Cultures that use legumes as a staple have long-standing customs in terms of garnishing. In Mexican cuisine, beans are traditionally cooked with a few sprigs of cilantro. In countries on the Mediterranean Sea, they are often garnished with extra virgin olive oil and a spray of red wine vinegar. 

Lentils are the fastest cooking legumes. They can make a hearty soup in just twenty minutes on a cold winter day or be added to a salad when temperatures are warmer. Indian cuisine uses lentils (daal) in dozens of ways, from making curry, to combining them with yogurt, or making pancakes.

There are thousands of recipes for legumes online. Most recipes are simple and easy to follow, with no need for additional ingredients. Legumes are so rich in flavor that they don’t need much to liven them up. Excessive salt should always be avoided.

A quicker approach is to heat up canned beans. Compared to other packaged foods, most bean confections have little processing. 

<p class="pro-tip">Tip: If you’re using canned beans, check to see if they contain added salt. If they do, don’t add additional salt to the dish you’re preparing.</p>

The rich nutritional profile of beans and other legumes makes them perfectly adaptable to a wide range of diets including:

Simple Ways to Eat More Legumes

The best way to increase your consumption of legumes is to be sure to have them in your pantry. Whether dried or canned, beans and lentils have a long shelf life. You can stock up with no risk of spoilage. Lentils are the quickest legume to cook, so always keep a bag or two on hand for a quick, delicious meal.

Adding beans and other legumes to your diet is easy. Eat them as snacks or combine them with foods you already eat to enhance flavor and texture.

  • Snacks: peanuts, edamame
  • Spreads: hummus made from chickpeas or beans
  • Soups: black bean, lentil, Italian pasta e fagioli
  • Salads: top with green beans, red beans, black beans, or cannellini 
  • Sauces: for a lentil curry, add some cumin, turmeric, and garam masala

<p class="pro-tip">Related: Easy Low-Glycemic Snacks</p>

Don’t ignore beans and other legumes as a source of nutrition. Adding them to your diet as a condiment, a side dish, or a featured meal is easy and very affordable. Their long shelf-life makes them a perfect item to store in your pantry year-round. 

Best of all, legumes are an important source of protein and essential nutrients with no fat or cholesterol. And they have a low glycemic index. As such, they complement a variety of diets, including the Mediterranean diet, the DASH diet, and vegetarian and vegan diets. 

Eating more legumes may be one of the simplest ways to eat more protein and fiber; while keeping your blood sugar levels stable. So, stock up on beans today!

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References

  1. https://pubmed.ncbi.nlm.nih.gov/19394480/
  2. https://www.itis.gov/servlet/SingleRpt/SingleRpt?search_topic=TSN&search_value=500059%23null
  3. https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/1384247
  4. https://pubmed.ncbi.nlm.nih.gov/12498625/
  5. https://pubmed.ncbi.nlm.nih.gov/18845707/
  6. https://academic.oup.com/ajcn/article/70/3/439s/4714906
  7. https://pubmed.ncbi.nlm.nih.gov/11718588/
  8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5391775/
  9. https://www.nature.com/articles/1601995%23ref-CR13
  10. https://pubmed.ncbi.nlm.nih.gov/19939654/
  11. https://www.dietaryguidelines.gov/
  12. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281997/

About the Author

Peter Palmieri Headshot
Peter Palmieri is a licensed physician in Texas. He practiced pediatrics for over 20 years in underserved communities.
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Please note: The Signos team is committed to sharing insightful and actionable health articles that are backed by scientific research, supported by expert reviews, and vetted by experienced health editors. The Signos blog is not intended to diagnose, treat, cure or prevent any disease. If you have or suspect you have a medical problem, promptly contact your professional healthcare provider. Read more about our editorial process and content philosophy here.

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