American Health & Medical Research Association
Myth and fact

Lentils and lollipops are both carbs, and only one earned the bad reputation

Carbohydrates fuel your brain and muscles, and one high-carb island diet came with no apparent heart disease. The evidence against carbs lands mostly on refined and highly processed ones.

By the Health Research USA editorial team

Published Last updated October 2026

Written from the sources listed below; links checked October 2026. It touches on medicines, doses or health conditions and has not yet been reviewed by a licensed clinician, so use it to prepare for a conversation with yours. How we research and review

Sources13, listed below Reading time15 minutes

Where the evidence stands

  • Strong evidence Refined grains, added sugars and sugary drinks harm heart and metabolic healthWhole grains are linked to lower death rates and less heart diseaseLower-carb eating improves blood sugar and blood fats in type 2 diabetesCarbs fuel hard endurance exercise better than fat
  • Not enough evidence Very high-carb diets raise death risk whatever the carb sourceTraditional high-carb diets protect the heart
  • Evidence says no, or unsafe All carbohydrates are harmful

Each use is rated separately, from the scorecard in this guide. Safety cautions are spelled out in the guide itself. How we grade

On this page
  1. The short answer: no, but some carbs earned their bad name
  2. What your body needs, and what it can do without
  3. Athletes show what carbohydrate is for
  4. Whole-food, high-carb traditions hold up better than the myth suggests
  5. The PURE study seemed to indict carbs. Look closer.
  6. What the new Dietary Guidelines say about carbs
  7. A carb quality sorter and three sample days
  8. How strong is the evidence?
  9. Who should talk with a clinician before changing carbs
  10. Questions readers ask
  11. The bottom line

Key takeaways

  • The recommended daily amount of carbohydrate is 130 grams, set to cover the brain’s glucose needs, though on very low intakes the body can burn fat and make ketones instead1.
  • On Kitava, an island in Papua New Guinea where oil, cereal grains and refined sugar supplied a median of 0.03% of calories, researchers found no apparent stroke or ischemic heart disease, even though most adults smoked56.
  • In the PURE study of 135,335 people in 18 countries, the highest-carb diets were linked to a 28% higher risk of death, but critics noted that many of those diets in poorer countries leaned on refined starch such as white rice78.
  • More than 80% of the carbohydrates Americans eat are low-quality ones such as refined grains, added sugars, juice and fries, the science report behind the new Dietary Guidelines found10.
  • Endurance athletes training one to three hours a day are advised to eat 6 to 10 grams of carbohydrate per kilogram of body weight, and elite race walkers on very low-carb diets missed out on race gains234.

In late 1990, Swedish researchers drew blood from people on Kitava, an island in Papua New Guinea’s Trobriand Islands5. The islanders lived on yams, sweet potatoes, taro, fruit, fish and coconut5.

Oil, cereal grains and refined sugar together made up a median of just 0.03% of their calories. Swedes, by comparison, got more than 70% of theirs from such foods and from dairy, margarine and alcohol5. The researchers described the island diet as high in carbohydrate and low in fat5.

In an earlier study, the lead researcher and a colleague found that stroke and ischemic heart disease, the kind caused by narrowed arteries, appeared to be absent on the island56. That was judged by interviews, heart tracings and clinical experience. And these were not health purists. About three in four men and four in five women smoked every day5.

Kitava can’t prove that starchy roots protect the heart. But it makes one claim hard to defend: that carbohydrates, as a group, are poison. This article covers what your body needs, what the big studies show, and how to sort the carbs on your plate.

The short answer: no, but some carbs earned their bad name

No. “Carbohydrate” is a broad word covering sugars, starches and fiber1, and it stretches from lentils, berries and sweet potatoes to soda, candy and white bread.

Carbohydrates supply almost half the calories Americans eat, according to the scientific report behind the 2025–2030 Dietary Guidelines10. But more than 80% of those carbs are what the report calls low quality: added sugars, refined grains and starches, fruit juices, and processed potato products like fries, chips and hash browns10.

That’s where the evidence of harm piles up. Randomized trials, where people are assigned by chance to one diet or another, show that refined grains, refined potatoes and added sugars hurt heart and metabolic health10.

Cutting carbs also helps some people. The same report found that lower-carb diets can improve blood sugar and blood fats, especially in type 2 diabetes10.

Both things can be true. Carbs as a class aren’t the problem, while the refined, highly processed versions mostly are.

What your body needs, and what it can do without

Your brain is the reason for the official number. In 2005, the National Academies (then called the Institute of Medicine) put the Recommended Dietary Allowance (RDA) for carbohydrate at 130 grams a day for anyone older than 11. The figure is meant to keep the brain and the rest of the nervous system supplied with the glucose they run on1.

The Academies’ broader advice is that carbs supply 45% to 65% of calories. On a 2,000-calorie day, that’s 225 to 325 grams1.

The 130 grams isn’t the only way to fuel the brain, though. Eat fewer than about 20 grams a day and your body switches strategies: it taps stored fat and turns some of it into ketones, a backup fuel the brain and muscles can burn1. Our keto article covers when doctors use that shift as therapy.

You also carry a modest glucose stockpile, tucked into liver and muscle cells1. Starch and sugar each supply 4 calories per gram1.

This is a useful bit of math. At 4 calories a gram, 130 grams equals 520 calories, about 26% of a 2,000-calorie day. Keep that in mind when you read about “low-carb” and “high-carb” studies below.

Athletes show what carbohydrate is for

If you want to see carbohydrate at work, watch an endurance athlete. In 2016, three professional groups issued a joint position on sports nutrition: the Academy of Nutrition and Dietetics, Dietitians of Canada and the American College of Sports Medicine2.

Their daily targets scale with training2:

  • Light training, such as skill work or low-intensity exercise: 3 to 5 grams per kilogram of body weight.
  • Moderate, about an hour a day: 5 to 7 grams per kilogram.
  • High, one to three hours a day of endurance training: 6 to 10 grams per kilogram.
  • Very high, more than four to five hours a day: 8 to 12 grams per kilogram.

For a 154-pound (70-kilogram) runner in the high group, that’s 420 to 700 grams a day, far above the RDA. The reason is glycogen, the stored form of glucose in muscle. When muscle glycogen runs low, fatigue sets in and athletes can’t hold their pace, the groups noted2.

What about training your body to run on fat instead? The position paper said high-fat, low-carb diets do raise fat burning, but performance at higher intensities suffers2.

Two studies of elite race walkers make the point. In a study in The Journal of Physiology, 29 walkers trained hard for three weeks on one of three diets3. Those on high-carb plans improved their 10-kilometer race times by 5% to 7%. Those on a very low-carb, high-fat diet, under 50 grams of carbs a day, didn’t improve, and walking at race pace took more oxygen3.

A 2021 study funded by Australian Catholic University tested a much shorter switch of five to six days4. Thirteen world-class male race walkers took part. In a 10,000-meter race, every athlete on the high-carb diet got faster, while six of the seven low-carb athletes got slower4. Their bodies still burned carbs poorly even after carbs were added back before the race4.

A light exerciser needs far less2. But the research shows carbs aren’t empty fuel. For hard, fast effort, the evidence favors them over fat.

Whole-food, high-carb traditions hold up better than the myth suggests

Back to Kitava. The Swedish team’s 1994 report is worth a closer look5.

The island diet wasn’t low in every kind of fat. Total fat was low, yet saturated fat, nearly all of it from coconut, may have supplied about 17% of calories, by the researchers’ rough estimate at an assumed calorie intake5.

What set Kitavans apart was their bodies. Compared with Swedes, they were leaner and had lower diastolic blood pressure, the bottom number, and in some age groups their total and LDL cholesterol ran 10% to 30% lower5. The authors’ best explanation for the missing stroke and heart disease was leanness and low blood pressure, with cholesterol perhaps helping a little5.

The authors were candid about the limits. A single survey can’t show cause and effect5. Among younger islanders, only 40% of those invited came, and volunteers made up part of the sample. Food intake was estimated, and activity went unmeasured5.

Other traditions tell similar stories, with their own caveats. Our paleo article describes the Hadza of Tanzania, hunter-gatherers who get a large share of calories from honey, berries and tubers. Our articles on heritage diets and on purpose and the Blue Zones explain why Okinawa’s famous longevity story needs care.

For readers who value tradition, this is good news. Beans, roots, grains and fruit have fed families for generations. The modern problem is the potato chip, not the potato.

The PURE study seemed to indict carbs. Look closer.

In 2017, the Prospective Urban Rural Epidemiology study, known as PURE, made headlines78. Researchers followed 135,335 people aged 35 to 70 in 18 countries for a median of 7.4 years7.

People in the top fifth for carbohydrate intake had a 28% higher risk of dying during the study than those in the bottom fifth7. Carbs weren’t linked to heart disease, while higher fat intake went with lower death rates7. The authors said global diet guidelines should be reconsidered7.

Critics, including nutrition scientists at Harvard’s School of Public Health, saw serious problems8:

  • Carbs were lumped together. The study tallied total carbohydrate, so a gram from beans or fruit counted the same as a gram from white rice or sugar8.
  • Poverty was tangled up with diet. In low-income countries, many participants ate mostly carbohydrate, much of it refined. In Bangladesh, for example, white rice was the leading source not just of carbohydrate but of protein and fat too8.
  • Few participants lived in the West. Only 11% came from Europe or North America, Susan Jebb of the University of Oxford pointed out11.

This is what got lost in the headlines. The highest-carb group got about 77% of calories from carbohydrate. The lowest-carb group still got about 46%8. That’s far above the roughly 26% that 130 grams supplies on a 2,000-calorie day.

PURE’s own lead author, Mahshid Dehghan, said moderate intake, around 50% to 55% of calories, was likely better than very high or very low11. Her team also stressed that it wasn’t recommending low-carb diets, with under 50% of calories from carbs11. In other words, PURE looks less like a case against carbs and more like a warning about diets built on refined starch with little else.

PURE is also an observational study. It tracks what people eat and what happens to them, so it can show links but can’t prove cause. Our article on observational studies explains why that matters.

What the new Dietary Guidelines say about carbs

The 2025–2030 Dietary Guidelines, released in January 2026, take a firm line on refined carbs. They tell Americans to cut back sharply on highly processed, refined carbohydrates, naming white bread, packaged breakfast foods, flour tortillas and crackers9.

They also recommend 2 to 4 servings of whole grains a day, 3 servings of vegetables and 2 of fruit on a 2,000-calorie pattern9. Beans, peas and lentils appear among the protein foods9. No amount of added sugar is recommended, and one meal should hold no more than 10 grams9.

The Guidelines also leave room for lower-carb eating. They say people with certain chronic diseases may do better on a lower-carbohydrate diet, chosen with a health care professional9.

The scientific report behind them frames its goal around helping people choose high-quality carbohydrate foods10. Its high-quality list: minimally processed vegetables, berries and other fruits, whole grains and beans10. Whole grains carried some of its strongest evidence, with high-certainty links to lower death rates and less heart disease10.

Our companion articles go deeper on fiber, glycemic index, whole grains and low-carb diets. This one focuses on sorting.

A carb quality sorter and three sample days

This sorter is our own tool, built from the sources above. Before you sort a food, ask three questions:

  1. Is it close to the way it grew?
  2. Does a serving bring about 3 grams of fiber or more?
  3. Is sugar or refined flour one of the main ingredients?
Tier What belongs here Examples, with fiber per serving How often
Build on these Beans, lentils, peas, whole fruit and vegetables, including starchy ones Navy beans 9.6 g and lentils 7.8 g per ½ cup; raspberries 8 g per cup; sweet potato 6.3 g per cup12 Most meals
Everyday sides Whole grains, potatoes with skin, corn, popcorn, plain milk and yogurt Bulgur 4.1 g per ½ cup; baked potato with skin 3.9 g; popcorn 5.8 g per 3 cups12 Daily; 2 to 4 grain servings9
Cut back Refined grains and starches White bread, crackers, flour tortillas, packaged breakfast foods9 Less often9
Plan, don’t graze Added sugars, sugary drinks, juice and processed potato products Soda, candy, pastries, fries and chips910 Planned treats; skip sugary drinks9

The natural sugar in plain milk doesn’t count as added sugar9.

Now the sample days. All three use whole foods. Carb counts come from a University of Florida table built on USDA data, so brands and portions will vary1. Use plain, unflavored oatmeal, and add protein foods, nonstarchy greens and healthy fats as you like.

Meal About 95 grams About 200 grams About 300 grams
Breakfast 6 oz plain Greek yogurt, 1 oz pecans, 1 apple (33 g) 1 packet instant oatmeal, 1 banana, 1 cup 1% milk (67 g) 2 packets instant oatmeal, 1 banana, 1 cup 1% milk (95 g)
Lunch Salad with ½ cup lentils and 1 carrot (26 g) Lentil soup with 1 cup lentils, 1 carrot, 1 apple (69 g) 1 cup black beans, 1 baked russet potato, 1 carrot (83 g)
Dinner Fish or tofu, 1 cup green beans, 1 medium sweet potato (34 g) Chicken or tofu, ½ cup black beans, 1 medium sweet potato, 1 cup green beans (54 g) 1 cup lentils, 1 medium sweet potato, 1 cup green beans (74 g)
Snack None needed Plain Greek yogurt with 1 oz pecans (10 g) 1 cup grapes and 1 apple (50 g)

The 95-gram day falls under 130 grams, the line the Guidelines’ report used for low-carb diets10. The 300-gram day fits the Academies’ range for 2,000 calories1. All three days are built from the top two tiers.

How strong is the evidence?

Claim Evidence level What the research shows
Refined grains, added sugars and sugary drinks harm heart and metabolic health Strong evidence Trials and long-term studies agree10
Whole grains are linked to lower death rates and less heart disease Strong evidence High-certainty pooled studies10
Lower-carb eating improves blood sugar and blood fats in type 2 diabetes Strong evidence Randomized trials reviewed for the Guidelines10
Carbs fuel hard endurance exercise better than fat Strong evidence Expert position and controlled athlete trials234
Very high-carb diets raise death risk whatever the carb source Not enough evidence PURE’s link is tangled with poverty and refined starch78
Traditional high-carb diets protect the heart Not enough evidence Striking snapshots like Kitava, but no trials5
All carbohydrates are harmful Evidence says no Whole grains are linked to lower death rates, and more vegetables and whole fruit lowered blood pressure in trials10

Who should talk with a clinician before changing carbs

  • You take insulin or other medicine that lowers blood sugar. The Guidelines say people with chronic diseases who try lower-carb eating should work with a health care professional9. Our low-carb article explains why doses may need to change.
  • You have a health condition and want to try very low-carb eating. The University of Florida guide warns that it can be risky for some people with certain conditions1.
  • You train hard. Fueling needs climb fast with training time, and the sports groups’ targets are a starting point for a sports dietitian2.
  • You’ve struggled with food rules or eating disorders. Sorting foods can tip into fear. Call the National Alliance for Eating Disorders helpline at 1-866-662-123513. If you’re in crisis, call or text 988.

Questions readers ask

Are potatoes bad for you?

Not as whole foods. A baked potato with skin has about 3.9 grams of fiber12, and Kitavans ate sweet potatoes as a staple5. The Guidelines’ report flagged processed potato products such as fries, chips and hash browns as low-quality carbs10.

Is fruit too high in sugar?

For most people, no. The Guidelines recommend two servings of fruit a day, and the sugar in whole fruit doesn’t count as added sugar9. A cup of raspberries brings 8 grams of fiber12. If you have diabetes, a dietitian can help you fit fruit into your plan.

How many carbs should I eat?

There’s no single right number. The Academies’ range is 45% to 65% of calories, the RDA is 130 grams, and athletes may need several times more12. The newest federal science report centers on carb quality10.

Is white rice off-limits?

No, but it belongs in the “cut back” tier. The Guidelines urge a sharp cut in refined carbs9, and PURE’s critics noted that the highest-carb diets in poorer countries leaned heavily on white rice8. Mixing white rice with beans and vegetables, or rotating in whole grains, is a practical middle path.

The bottom line

Carbohydrates aren’t inherently bad. Your brain and muscles run on them, athletes perform best with them, and islanders who ate mostly starchy roots and fruit showed no apparent stroke or heart disease.

The trouble lies with refined grains, added sugars, sugary drinks and processed potato snacks, which make up most of the carbs Americans eat. Build your meals on beans, fruit, vegetables and whole grains, keep refined carbs to a minimum, and choose your carb level, low or high, with your health and activity in mind.

About this article

This article was researched using the 2025–2030 Dietary Guidelines and their scientific report, USDA data, a university extension guide, a sports nutrition position paper, and peer-reviewed studies, all listed below. It was reviewed in October 2026. It is general education and not medical, legal or financial advice.

Sources

  1. Gal NJ, Ford AL, Dahl W. “Facts about Carbohydrate” (FSHN14-03). UF/IFAS Extension, revised January 2026. ask.ifas.ufl.edu
  2. Dietitians of Canada, Academy of Nutrition and Dietetics, and American College of Sports Medicine. “Nutrition and Athletic Performance” (joint position paper). Medicine & Science in Sports & Exercise, 2016 (PDF copy). gomotionapp.comdoc/364857_2_noap-position-paper.pdf
  3. The Journal of Physiology. “Low carbohydrate, high fat diet impairs exercise economy and negates the performance benefit from intensified training in elite race walkers.” 2017;595(9):2785–2807 (LIDA sports database record). lida.sport-iat.de
  4. Burke LM, Whitfield J, Heikura IA, et al. “Adaptation to a low carbohydrate high fat diet is rapid but impairs endurance exercise metabolism and performance despite enhanced glycogen availability.” The Journal of Physiology, 2021 (Australian Catholic University record). acuresearchbank.acu.edu.au
  5. Lindeberg S, Nilsson-Ehle P, Terént A, Vessby B, Scherstén B. “Cardiovascular risk factors in a Melanesian population apparently free from stroke and ischaemic heart disease: the Kitava study.” Journal of Internal Medicine, 1994 (PDF copy). Gwern.net
  6. Lindeberg S, Lundh B. “Apparent absence of stroke and ischaemic heart disease in a traditional Melanesian island: a clinical study in Kitava.” Journal of Internal Medicine, 1993 (Global Health Data Exchange record). ghdx.healthdata.org
  7. Dehghan M, Mente A, Zhang X, et al. “Associations of fats and carbohydrate intake with cardiovascular disease and mortality in 18 countries from five continents (PURE): a prospective cohort study.” The Lancet, 2017 (Food and Behaviour Research record). pubmed.ncbi.nlm.nih.gov
  8. Harvard T.H. Chan School of Public Health. “PURE study makes headlines, but the conclusions are misleading.” The Nutrition Source, September 8, 2017. nutritionsource.hsph.harvard.edu
  9. U.S. Department of Health and Human Services and U.S. Department of Agriculture. “Dietary Guidelines for Americans, 2025–2030.” January 2026. cdn.realfood.gov
  10. U.S. Department of Health and Human Services and U.S. Department of Agriculture. “The Scientific Foundation for the Dietary Guidelines for Americans, 2025–2030.” 2026. cdn.realfood.gov
  11. FoodNavigator. “Trimming the fat off dietary guidelines: Study links high carb intake to mortality risk.” August 29, 2017. foodnavigator.com
  12. U.S. Department of Agriculture and U.S. Department of Health and Human Services. “Dietary Fiber: Nutrient-dense Food and Beverage Sources” (FoodData Central, 2019). 2020–2025 Dietary Guidelines online materials. DietaryGuidelines.gov
  13. National Alliance for Eating Disorders. “What Is an Eating Disorder Helpline?” Accessed October 2026. allianceforeatingdisorders.com