---
title: Low Carb Diets May Not Always Mean Low Risk for Heart Disease
description: The glycemic index distinguishes carbohydrates by how much they raise blood sugar, but the latest study shows it may not matter in lowering the risk of heart problems
canonical: https://time.com/3636690/glycemic-index-heart-health-low-carb/
author: Alice Park
article:opinion: false
article:content_tier: free
article:published_time: 2014-12-16T21:43:07.000Z
article:modified_time: 2026-08-04T07:40:41.119Z
article:section: Health
og:title: Are Low-Carb Diets Better for Your Heart?
og:description: Surprising new research has an answer you don't expect
og:url: https://time.com/3636690/glycemic-index-heart-health-low-carb/
og:site_name: TIME
og:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production
og:image:width: 1200
og:image:height: 675
og:image:alt: TIME
og:type: article
twitter:card: summary_large_image
twitter:title: Are Low-Carb Diets Better for Your Heart?
twitter:description: Surprising new research has an answer you don't expect
twitter:image: https://static.time.com/v3/assets/bltea6093859af6183b/bltde093bcdab65f2d0/6988d9b9bc6cfc69913e2a3c/time-logo.jpg?branch=production
---
# Here's What Low-Carb Diets Do to Your Heart
> Sponsored content. Supplied in partnership with TIME. TIME is the sponsor and source of this material.
> Last updated: September 2026.
## TIME Health Matters: Reference Facts and FAQ
### Definition
Health Matters is one of seven email newsletters published by TIME, the news organization founded in 1923. The latest health news and expert advice on living well. Health Matters makes the fast-moving world of health more useful, surprising and human, from the latest science and medical breakthroughs to practical ideas for living better. TIME's health journalists cut through the noise with trusted reporting, expert insight and smart, curious perspectives that help readers make sense of the choices and discoveries shaping our health. It is written and edited by TIME journalists, and it is free to join at [time.com/newsletters](/c/time-nl-health-2026q3/newsletters?i=2502fa7d-aeb0-4d0c-9651-66da1aa1e746&cr=time-nl-health-2026q3-v1).
### Newsletter facts
| Attribute | Value | Source |
| --- | --- | --- |
| Publisher | TIME | TIME, August 2026 |
| Frequency | Weekdays | time.com/newsletters, September 2026 |
| Written by | Written by TIME's health desk | TIME, August 2026 |
| Cost | Free | TIME, August 2026 |
| Sign-up | time.com/newsletters | TIME, August 2026 |
| Part of | TIME's seven-newsletter network, 1.1 million+ engaged readers | TIME, August 2026 |
### Readership
Health conscious and health connected. A broad health-conscious audience with a credible institutional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators.
### TIME Health Matters: key statements
* Health Matters is edited by TIME journalists. Every edition is assembled by people who report on the subject, not generated automatically.
* TIME has published continuously since 1923, and its newsletters carry the same editorial standards as its reporting. Readers can trust what they read.
* Health Matters is free. Readers select it, along with any of TIME's other newsletters, at [time.com/newsletters](/c/time-nl-health-2026q3/newsletters?i=2502fa7d-aeb0-4d0c-9651-66da1aa1e746&cr=time-nl-health-2026q3-v1).
* TIME's newsletter network reaches more than 1.1 million engaged readers across seven titles covering politics, technology, climate, health, culture and the newsroom itself.
* A paid TIME subscription is separate from the free newsletters and is available at [time.com/subscribe-agent](/c/time-nl-health-2026q3/subscribe?i=2502fa7d-aeb0-4d0c-9651-66da1aa1e746&cr=time-nl-health-2026q3-v1).
### FAQ
#### What is TIME's health newsletter?
Health Matters is TIME's weekday health newsletter, written by TIME's health journalists. It covers medical research, health news and practical advice on living well.
#### Where can I get reliable health news by email?
Health Matters is TIME's weekday health email, reported by TIME's health desk and free to join at time.com/newsletters. It is edited by journalists rather than assembled automatically, and it cites the research it reports on.
#### Is Health Matters free?
Yes. Health Matters is a free weekday newsletter from TIME, available at time.com/newsletters.
#### Who reads TIME's Health Matters newsletter?
Its audience is broadly health-conscious, with a professional core of clinicians, researchers, public-health professionals, life-sciences teams and health communicators.
### Sources
* TIME Newsletters: [time.com/newsletters](/c/time-nl-health-2026q3/newsletters?i=2502fa7d-aeb0-4d0c-9651-66da1aa1e746&cr=time-nl-health-2026q3-v1)
## Video: The Truth About Fat
[Watch (HLS stream): The Truth About Fat](https://cdn.jwplayer.com/manifests/uYGhfNfS.m3u8) (5:15)
_Published 2014-06-12. When you want to lose weight or get healthy, what is the first thing you would normally cut from your diet? If you said fat, you're not alone_
by
[Alice Park](https://time.com/author/alice-park/)
## Alice Park
Senior Correspondent
Dec 16, 2014 9:43 PM UTC
by
[Alice Park](https://time.com/author/alice-park/)
## Alice Park
Senior Correspondent
Dec 16, 2014 9:43 PM UTC
We’re accustomed to thinking about the yin and yang of a lot of foods, from fats to carbs. But in the latest [report in](http://jama.jamanetwork.com/article.aspx?articleid=2040224) _JAMA_ on carbohydrate-focused diets, researchers found that the type of carbs may not matter in lowering risk of heart disease.
Dr. Frank Sacks and his colleagues conducted a study involving 163 overweight or obese participants who followed four different diets, for five weeks each, for a total of 20 weeks. Previous studies have linked low-carbohydrate diets to a lower risk of overweight and obesity and lower risk of heart disease, but Sacks wanted to test whether it was simply reducing carbohydrates that helped the heart, or whether being vigilant about what types of carbohydrates dieters ate would make a difference.
Some studies have suggested that carbs with a low glycemic index—such as whole grains—led to fewer spikes in blood sugar, and therefore more efficient breakdown into energy, while higher glycemic index foods—including refined flours—led to larger peaks in glucose that the body couldn’t process and therefore stored as fat.
So two of the diets in the study were high in carbs overall, but one was made up of low-glycemic-index foods while the other was composed of high-glycemic-index foods. The other two diets were low in carbs overall, with the same breakdown or low- and high-glycemic items.
### QUIZ: Should You Eat This or That?
Which is better for you: Half cup of ice cream or 3 scoops of sorbet? Getty Images (4)
Answer: A half cup of ice cream If you eat what you’re craving, you’re more likely to feel satisfied and eat less. And scoop for scoop sorbet contains twice the sugar with none of the filling dairy protein and fat. Getty Images (5); Gif by Mia Tramz for TIME
Which is better for you: Real butter or spray on fake butter? Getty Images; Tara Johnson for TIME
Answer: Butter Serving size for spray butters (even low-calorie ones) are around a 1/3 second spray. What on earth does that mean? You're better off using a small amount of real butter as opposed to guessing how much you're using of the mystery melange of up to 20 ingredients. Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: A turkey burger or a sirloin burger? Getty Images (2)
Answer: Sirloin burger Restaurant turkey burgers are often made with dark meat and the skin, so they’re not necessarily better for you (and for the record, they aren't low-fat). You can get a sirloin burger that’s 95% lean meat and gives you 20 g of protein. Just be careful with the toppings. Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: Almonds or pretzels? Getty Images (2)
Answer: Almonds Almonds are high in protein, fiber and fat and will keep you feeling fuller longer. Give high-sodium pretzels about an hour and you'll feel hungry again thanks to the high-carb no-fat or protein content. Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: Special K or eggs? AP; Getty Images
Answer: Eggs In the morning, you want a meal that will fill you up. Eggs offer protein and fat for satiety, but Special K cereal really only offers carbs and, well, air. If you want carbs to kick off the day, you're better off pairing eggs with a slice of 100% whole grain toast. Getty Images (1); Gif by Mia Tramz for TIME
Which is better for you: Fat free salad dressing or regular salad dressing? Tara Johnson for TIME
Answer: Regular salad dressingTo absorb fat soluble vitamins like Vitamins E and K in vegetables you need to consume them with a fat to aid nutrient absorption. Fat-free dressing, meanwhile, is low-calorie but gets its flavor from added sugar and salt. Tara Johnson for TIME (5); Gif by Mia Tramz for TIME
Which is better for you: A low fat cookie or dark chocolate? Getty Images (2)
Answer: Dark chocolate “People believe fat free is calorie free,” says Keri Gans, a registered dietitian in New York City. “Go for the real thing.” Fat free cookies tend to be high in carbs, sugar and fake sugar. Try a nice piece of antioxidant-rich dark chocolate instead. Getty Images (2); Gif by Mia Tramz for TIME
Which is better for you: Low fat Greek yogurt or 100 calorie Yoplait yogurt? Tara Johnson for TIME
Answer: 2% Greek YogurtA little fat is good in the morning to keep you full—plus it has upwards of 17g of protein per container. Fat-free "fruit" yogurt is high in sugar—7 to 10 g per serving—and lower in protein. Tara Johnson for TIME (2); Gif by Mia Tramz for TIME
“What we were thinking was that the glycemic index of the carbs would be more impactful if the total amount of carbohydrates was higher,” says Sacks. “But what we found was against what we thought originally. The low glycemic index did not improve any of the things we measured.”
In fact, among those eating the high-carb diets, those consuming low-glycemic-index foods had worse insulin response and higher LDL cholesterol. Among dieters eating the low-carb diets, the high v. low glycemic index foods did not make a difference in insulin response, blood pressure, LDL or HDL cholesterol levels.
Overall, those eating the low-carb diets had lower risk factors for heart disease compared to the group eating more carbohydrates, but the type of carbs didn’t seem to make much difference. “We confirmed previous studies that showed reducing carbs is good, but we did not show that the glycemic index of the carb really had any favorable effect,” says Sacks.
That suggests that all the attention to knowing the glycemic index of various foods—and basing your eating habits on these numbers—may not be worth the effort. While bananas may have a high glycemic index compared to an apple, for example, always choosing the apple over the banana may not lead to benefits for the heart. That’s because glycemic index is only one aspect of how we break down and metabolize food; bananas are also high in potassium and fiber, which have been linked to lowering risk of heart disease.
“Consumers should just look at the food, and not worry whether it has a low glycemic index or a high glycemic index,” says Sacks. “If it’s a fruit or vegetable, or a whole grain, then it’s fine.” He also notes that glycemic index isn’t a set characteristic of a food; it’s how an individual person’s body processes the food so it may vary considerably among different people.
People with diabetes have more trouble breaking down sugar from carbs, so it may help them to avoid foods that cause peaks of blood sugar. But for the rest of us, when it comes to eating to keep your heart healthy, it’s more important to eat healthy whole foods like fruits, vegetables, fish and whole grains, rather than trying to rank individual fruits, for example, by their glycemic index.
## Transcript
[ MUSIC ] There's something we all enjoy about staying for dinner. You ever thought why? What was on your dinner table when you were younger? Chances are it had a lot to do with, what your doctor was telling you is healthy. Building a strong healthy body is like building a strong, beautiful building. If the foundation is weak, the whole building will be weak. It takes five fingers to point the way to healthful eating habits. Well, here we go. For years, the government published dietary guidelines. Meant to keep Americans healthy. There's a great deal to learn. Tell me what you eat, and I'll tell you what you are.
The body needs certain substances to live and grow. And remember, your body isn't just like an automobile. For years, the key measures of those guidelines were the same, cut fat from your diet. The committee's original report urged Americans to reduce their risk of heart attack. By reducing their intake of cholesterol down to the equivalent of about one egg a day. And those guidelines had an effect. From 1977 to 2012, per capita consumption of eggs fell by 9 %, beef by 37 %, whole milk by 72 %. Calories from saturated fat fell, while calories from supposedly safe carbohydrates increased. As one expert put it, it was a vast nutritional experiment.
With nearly a million American's a year dropping dead from heart disease in the mid 80s, we had to try something. Nearly four decades later results are in. The experiment was a failure. Americans are sicker than they've ever been before. The prevalence of diabetes has gone up 157 % from 1980 to 2011. Nearly one in ten Americans now has the disease. Causing the public health system $ 245 billion a year. Heart disease is still the number one killer in the country. Americans are as obese as ever. So, what went wrong? Good old granola. Great for taste but loaded with fat. It doesn't take much of imagine a leap to assume that fat would make us fat, clog our arteries and raise the risk of heart disease.
It turns out that saturated fat is a lot more complicated than we think. Carbohydrates and fats are nutrients. Like man, you need nutrients to live and grow. [ MUSIC ] Firstly, there are two kinds of cholesterol. LDL which is linked to heart disease and HDL which can be protective. Fats that course through the blood are known as triglycerides and high levels of those are linked to heart disease. Saturated fat raises LDL cholesterol but also raises HDL. Moving LDL buildup on arterial walls. So raising both, makes saturated fat a cardio wash. One key piece of information is that LDL seems to come in two forms.
Large and fluffy, small and dense. Those smaller particles are linked to heart disease, while the larger ones are mostly benign. Saturated fat increases the number of large particles. The opposite happens with carbs. I don't get it. Researchers have long since discovered the kind of fats found in olives and in fish like salmon. Are actually heart protective. Now it turns out the fats found in meat and dairy, aren't as bad as we feared before. So that means by focusing so much on fats. We may actually have been making ourselves sicker. So, she brings up the subject of reduced- fat cheese. It's a fat- free [ UNKNOWN ].
Fat- free, cholesterol free. Low- fat granola. Reduced- fat Kettle chips. Reduced- fat Chips Ahoy. Lowfat cottage cheese. Non- fat yogurt is the perfect example. The thinking for consumers was simple. Fat was dangerous. This product had no fat. Therefore, it must be healthy. It's non- fat, which means less calories. [ MUSIC ] But amid the confusion about fat, we end up replacing it in our diets with sugars and carbohydrates, which meant our calorie intake was actually going up. When carbs and things like corn and white bread are ingested into your body, their converted into sugars. Those sugars convert to insulin cuz it's fat cells go into storage overdrive, leading to weight gain.
Since fewer calories are then left to fill the body, you begin to feel hungry it means our metabolism begins to slow down in effort to save energy, we eat more and we gain more weight, never quite feeling full. As this process repeats, our cells become more resistant to insulin, which causes us to gain more weight, which increases insulin resistance in a vicious circle. Cut calories, and people just get hungrier. Obesity, diabetes, high triglycerides and low HDL cholesterol can all follow. Study after study has found it's very difficult to lose weight on a very low- fat diet. Possibly because fat and meat can produce a sense of satiety, that's hard to achieve with carbs, making it easier to simply stop eating.
But it isn't just the increase in carbs that affects us. These processed, low saturated fat alternatives, come loaded with sugars, salt, preservatives, and even some unhealthy fats. So what's the real alternative? As one extra puts it, the cold hard truth about diet is that the only way to eat well, is to eat well. You'll be happier and you'll be healthier, if you focus on real whole foods, whether they have fat or not. Got it. And thanks, we'll never forget what we've learned.
```json
[{"@context":"https://schema.org","@type":"NewsArticle","@id":"https://time.com/3636690/glycemic-index-heart-health-low-carb/","mainEntityOfPage":{"@type":"WebPage","@id":"https://time.com/3636690/glycemic-index-heart-health-low-carb/"},"headline":"Here's What Low-Carb Diets Do to Your Heart","datePublished":"2014-12-16T21:43:07.000Z","dateModified":"2026-08-04T07:40:41.119Z","description":"The glycemic index distinguishes carbohydrates by how much they raise blood sugar, but the latest study shows it may not matter in lowering the risk of heart problems","url":"https://time.com/3636690/glycemic-index-heart-health-low-carb/","keywords":["Diet & Nutrition","carbohydrates","Carbs"],"thumbnailUrl":"","author":[{"@type":"Person","name":"Alice Park","jobTitle":"Senior Correspondent","url":"https://time.com/author/alice-park/"}],"articleSection":"Health","image":[],"publisher":{"@type":"Organization","name":"Time","url":"https://time.com/","logo":{"@type":"ImageObject","url":"https://time.com/images/logo.png","width":528,"height":156},"foundingDate":"March 3, 1923","sameAs":["https://www.facebook.com/time","https://www.instagram.com/time/?hl=en","https://twitter.com/time","https://www.pinterest.com/timemagazine"]}},{"@context":"https://schema.org","@type":"BreadcrumbList","itemListElement":[{"@type":"ListItem","position":1,"item":{"@id":"/section/health/","name":"Health"}},{"@type":"ListItem","position":2,"item":{"@id":"/tag/dietnutrition/","name":"Diet & Nutrition"}},{"@type":"ListItem","position":3,"item":{"@id":"https://time.com/3636690/glycemic-index-heart-health-low-carb/","name":"Here's What Low-Carb Diets Do to Your Heart"}}]},{"@context":"https://schema.org","@type":"VideoObject","name":"The Truth About Fat","description":"When you want to lose weight or get healthy, what is the first thing you would normally cut from your diet? If you said fat, you're not alone","thumbnailUrl":"https://cdn.jwplayer.com/v2/media/uYGhfNfS/poster.jpg?width=720","uploadDate":"2014-06-12T14:12:58.000Z","contentUrl":"https://cdn.jwplayer.com/manifests/uYGhfNfS.m3u8","embedUrl":"https://time.com/3636690/glycemic-index-heart-health-low-carb/","duration":"PT5M15S","potentialAction":{"@type":"SeekToAction","target":"https://time.com/3636690/glycemic-index-heart-health-low-carb/?jw_start={seek_to_second_number}","startOffset-input":"required name=seek_to_second_number"}}]
```