The other day, I got asked – should I eat legumes? And Are legumes making me fat?

I figured these questions were the start of an important blog post.

So in this post, I’ll be covering:

  • What are legumes?
  • Should I eat legumes?
  • And, are legumes making me fat?

Legumes aren’t suitable for every body type, so knowing your body type and the foods that work best for you means you can choose foods that make you feel good, all the time.

What are legumes?

Should I Eat Legumes | Downsize Me

Legumes are pretty much beans and peas. They belong in the botanical family Fabaceae.

Dried legumes are sometimes called pulses.

The list of legumes include:

  • Alfalfa
  • Red kidney beans
  • Cannellini beans
  • Navy (haricot) beans
  • Boston beans
  • Broad (fava) beans
  • Butter beans
  • Snake beans
  • Adzuki beans
  • Mung beans
  • Black-eyed beans
  • Soybeans
  • Green peas
  • Snow peas
  • Snap peas
  • Chickpeas
  • Lentils (red, green, brown, puy, urad) and
  • Lupins
  • Licorice
  • Peanuts
  • Red clover

You can buy them split, in flours, canned, dried, frozen or fresh.

The Nutritional Value of LegumesShould I Eat Legumes | Downsize MeAs a scientist, I learned long ago that words like low, medium and high are meaningless without context.

So when people say legumes are high in protein, I say “compared to what?”

Let’s compare legumes with animal foods – specifically, milk and meats (red meat, chicken & fish).

Data source: Alan Borushek, 2017

When you compare 100g of each, the facts are pretty clear:

  • Meat, chicken and fish are predominantly made of protein (with some fat)
  • Legumes are predominantly made of carbohydrates (with some protein and fibre)
  • Milk is a relatively even mix of protein, carbs and fat (but with lower total amounts than meats and legumes).

Wrapping it up, you could say that legumes are a low-fat (< 3%) source of plant protein that are predominantly made up of carbohydrates, including fibre.

Cooking reduces the protein content of legumes to around 8%.

Phytates – An Anti-nutrient

When the phytic acid in a legume binds to minerals (e.g. calcium, iron, magnesium, zinc) it is known as phytate.

Phytate basically binds nutrients to prevent your body from using them. That’s why phytates are known as an anti-nutrient.

Vegetarians typically eat a phytate-rich diet which can reduce absorption of key nutrients like iron by up to 50%.

Proper food preparation and perhaps supplementation are required to counteract this, including vitamin C and vitamin D.

In some people phytates can cause inflammation, bloating and gas. Soaking dried legumes overnight, and cooking them properly or fermenting them, ‘disables’ a large portion of the phytates.

Even so, some people still suffer gastric upset or nutrient deficiencies (especially vegetarians).

Lectins

Should I Eat Legumes | Downsize Me

Lectins are a part of the legume that bind carbohydrates, and they are hard to digest.

The lectin phytohaemagglutinin, found in legumes, is toxic to humans in large doses.

In certain people, lectins can:

  • bind with your intestinal lining and cause damage and subsequently, nutrient deficiencies, or
  • start an immune response (e.g. autoimmune disease1, 2), or
  • they can bind to red blood cells causing clumping and anaemia2.

Common reactions may include irritable bowel syndrome, fatigue, insomnia, arthritis, hay fever, eczema, hives, gallbladder disease, diarrhea, nausea, achiness, anaemia, colitis, bowel lesions, neurological disorders and immune exhaustion.

Certain races and blood types can tolerate lectins better than others1.

According to Dr Laura Power:

  • A blood types seem to have the poorest tolerance and most reactions to lectins
  • O blood types seem to have the greatest tolerance and fewest reactions to lectins

All blood types experience red blood cell clumping with most types of beans.

And in fact, it’s no surprise that the top allergens in the world – dairy, egg, wheat, soy, peanuts, tree nuts, fish and shellfish – contain among the highest amounts of lectins compared to other foods.

Although they can be partly neutralised through soaking, proper cooking and/or fermentation, plant lectins can survive human digestion which means they can easily penetrate the gut and cause damage.

Should I eat legumes?

It’s crunch time.

You want to know – should I eat legumes?

Legumes are probably ok if you’re:

  • A vegetarian needing non-animal protein
  • An O blood type
  • An ectomorph body type
  • Someone who has no family history or personal diagnosis of autoimmune or digestive issues.

It’s probably best to avoid legumes if you’re:

  • An A, B or AB blood type
  • Someone who has a family history or diagnosis of digestive issues or autoimmune disease.
  • Someone with any sort of mineral deficiency including osteoporosis, tooth decay
  • Pregnant
  • Dealing with a serious illness
  • An endomorph body type.

If you DO decide to eat legumes, then you need to soak (dried legumes) overnight, drain them and cook them for at least 10 minutes to disable most of the anti-nutrients, phytates and lectins.

Finally, are legumes making me fat?

Based on what you’ve read above, I’m sure you’ll agree when I say ‘it depends’.

Being bloated can feel like you’re fat

If you have digestive issues or an autoimmune disease, or are an A, B or AB blood type, then legumes might be causing bloating and gas.

A bloated stomach can look and feel like a fat stomach, whether or not it actually IS.

Some people get fat if their carbohydrate intake is too high, especially if they’re inactive

For some people, like inactive mesomorphs or endomorph body types, a lower carbohydrate diet will help you to maintain a lower body weight.

If you ARE one of these types, and assuming the blood type and gut thing are both ok, then it’s best to consider your legumes as more like a carbohydrate and to use them sparingly. 

That way, you will probably get your total carbohydrate intake and portion size of legumes right to maintain a healthy weight.

References

1 Hungerford, Dr Carole. (2009) Good Health in the 21st Century. A Family Doctor’s Unconventional Guide. Scribe Publications, Melbourne, Victoria.

2 Power, Dr Laura. (1991) Dietary Lectins: Blood Types and Food Allergies. Townsend Letter for Doctors, December 1991. Virginia, USA.

Melanie White

Melanie White

Chief Inspiration Coach

I'm a quirky scientist and a Health and Wellness Coach who helps 35+ women to understand and eat right for their body type.