Leptin and Lectins: What’s the Difference?

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Leptin and Lectins: What’s the Difference?

If you like keeping up with the latest in health, nutrition, and the diet world, you may have come across terms that are somewhat similar-sounding: leptin and lectins. Are they the same? Or completely different? Read on if you’re curious to find out!


Leptin is a hormone made from fat cells in the body. The main role of leptin is to regulate fat storage, earning it the names “obesity hormone” or “fat hormone.” This hormone was discovered in 1994 with high hopes of it being a treatment for obesity.

Leptin works by signaling the brain that your body has enough energy stored in your fat cells. If leptin levels drop beyond your normal threshold, due to eating less and losing weight, for example, the brain sounds an alarm to help boost leptin levels in order to avoid starvation. It does this by stimulating the vagus nerve that runs between the brain and the stomach. Once the vagus nerve is stimulated, it makes you hungry and causes you to eat. This, in turn, leads to fat storage in your fat cells and restores normal leptin levels.

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One reason that leptin has been circulating on the internet lately is the book “The Leptin Diet.” Written by board-certified clinical nutritionist Byron J. Richards, the leptin diet is supposed to regulate leptin levels, keeping you feeling full. The guidelines of this diet are as follows:

  • Never eat after dinner or within three hours of bedtime.
  • Eat three meals a day, with five to six hours between each meal.
  • Stop eating when you are slightly less than full.
  • Eat about 20-30 grams of protein at breakfast.
  • Reduce your carb intake, but don’t completely stop eating it.

The diet also recommends consuming 400-600 calories per meal; eating a wide variety of foods; and avoiding sweeteners, diet soda, and soy products. Does this diet work? It could, if you follow it. From an eating-habit standpoint, it’s pretty reasonable. However, it’s not much different than many other diets out there. Talk with your doctor or dietitian if you are interested in trying this eating plan.


Lectins have also been in the news. Lectins are proteins that bind to carbohydrates. All plants contain lectins, but some have more than others, including:

  • Legumes (beans, peas, lentils)
  • Peanuts
  • Potatoes
  • Eggplant
  • Tomatoes
  • Fruits
  • Grains

Some lectins are safe to consume; others may potentially be harmful, earning lectin the name “anti-nutrient.” And one food, the castor bean, contains a lectin called ricin that can be lethal.

Lectin proteins can block the absorption of some minerals, such as iron, calcium, phosphorus, and zinc. They may also cause an autoimmune response that could play a role in inflammatory conditions such as rheumatoid arthritis and type 1 diabetes, according to the Harvard T.H. Chan School of Public Health. Because of the potential negative impact of lectins on health, an anti-lectin movement has been fueled. Notably, a book calling out lectins for causing weight gain and a number of chronic conditions is “The Plant Paradox: The Hidden Dangers in ‘Healthy’ Foods that Cause Disease and Weight Gain,” by Dr. Steven R. Gundry. Dr. Gundry claims that lectins are toxic and should be avoided because they can lead to inflammation, intestinal damage, and weight gain.

Again, while some lectins may be harmful, not all are. Legumes and whole grains, for example, are rich in nutrition and provide a number of health benefits. Also, cooking and processing can break down lectins, hence solving the potential risk of eating them. Some high-lectin foods shouldn’t be eaten in their raw state, such as beans, soybeans, potatoes, and whole grains (chances are, you wouldn’t be eating these foods raw, anyway).

The Plant Paradox diet can be hard to follow, as it restricts many foods, including:

  • Beans and legumes
  • Grain- or soy-fed livestock
  • Whole grains
  •  Nuts and seeds
  • All fruits except berries
  • Greek yogurt and cottage cheese
  • Canola, corn, peanut, sunflower, soybean oil

There is little evidence to support this diet’s claims. If someone does have a lectin sensitivity that might cause, say, digestive issues, a solution is to eat less of the food or eat it less often. Keep in mind that foods containing lectins are linked with lower rates of heart disease, obesity, and type 2 diabetes. The benefits of eating these foods outweigh the potential harm.

Want to learn more about eating well with diabetes? Read “Strategies for Healthy Eating,” “Improving Your Recipes: One Step at a Time,” and “What Is the Best Diet for Diabetes?”

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES

Amy Campbell, MS, RD, LDN, CDCES on social media

A Registered Dietitian and Certified Diabetes Educator at Good Measures, LLC, where she is a CDE manager for a virtual diabetes program. Campbell is the author of Staying Healthy with Diabetes: Nutrition & Meal Planning, a co-author of 16 Myths of a Diabetic Diet, and has written for  publications including Diabetes Self-Management, Diabetes Spectrum, Clinical Diabetes, the Diabetes Research & Wellness Foundation’s newsletter, DiabeticConnect.com, and CDiabetes.com

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