Ask a Doctor: How Bad is Sugar, Really Really?

I’ve yet to live through a full rotation on this planet without encountering at least one rumor about a new food that is probably going to kill me, like, yesterday. Food is a bigger rumor-starter than Jennifer Anniston’s occupied-or-is-it-unoccupied womb (which you know is a serious statement if you’ve ever stood in line at a grocery store).

The current target of dietary gossip? Sugar. You know, that thing that makes you feel really good and happy when you eat it. Because of course.

In an effort to squash some rumors in favor of some capital-T Truth, we sought out the advice of real-life expert gastroenterologist Sarah Diamond MD. Dr. Diamond is the Assistant Professor of Medicine at Oregon Health and Science University in Portland, Oregon, and she spends a lot of her time thinking about how the food we put in our mouths affects our bodies.

Have you heard the theory that sugar might be the new smoking? As in, evidence will suggest it’s directly linked to deadly diseases and that those diseases are preventative by not consuming the sugar?

I haven’t actually heard that sugar is the new smoking (I have heard that about sitting though…which is why I am currently walking around my living room as I am typing this), but there is definitely an emphasis right now on the detrimental effects of sugar (in particular, added sugar) on health. And there are well-described associations between diets high in sugar (in various forms) and an increased risk of insulin resistance, type 2 diabetes, cardiovascular disease and even some types of cancers.

That being said, the relationship between diet and disease is complex and it’s not yet been shown (to my knowledge) that simply avoiding sugar can prevent particular diseases.

I think that consumers need to be careful about listening to dietary trends that label a particular food or food group as evil. Remember in the ’90s when fat was considered the devil? So much so that we were led to believe that eating an entire box of Fat Free Snackwell cookies was totally ok? But now we recognize that dietary fat can be good for you and is in fact an important part of a healthy diet (why else would avocado toast be so popular?!). Sugar (or perhaps carbs, more broadly) seems to be the popular scapegoat these days but we probably need to be cautious about thinking of a particular food group, or type of food, as all good or all bad.

So how bad is sugar for you REALLY?

This is actually a difficult question. The truth is, it probably depends on a variety of factors. For starters, sugar comes in various forms (glucose, sucrose, fructose, simple carbohydrates, etc) and each of these may have a slightly different metabolic effect.

Some forms of sugar (for example high fructose corn syrup that can be found in sugar sweetened beverages like soda and juice) have very little (read: no) nutritional value and can not only lead to weight gain and metabolic syndrome but can also reduce the consumption of key nutrients because they replace the consumption of nutrient-dense foods.

But other kinds of sugar occur naturally in whole foods that are an important part of a balanced diet (think fruits, vegetables, starches) so when consumed in moderation play a key role in metabolism.

So natural sugars are okay? Dates won’t hurt me?

Naturally occurring sugars being “better” is related to the other macro and micronutrients that are consumed with them (for example, fruit is high in sugar but also contains fiber which is important to digestive health, cardiovascular health, etc).

Dates are a concentrated source of glucose and sucrose that also contain other essential nutrients, vitamins and minerals. So dates are a good choice if you are looking for a natural sweetener!

Funny you should bring up dates though, because, interestingly, there is a rare disease called hereditary fructose intolerance that leads to symptomatic hypoglycemia (low blood sugar) in response to consuming dates. But this condition is most prevalent in Saudi Arabia and is rare even there so dates probably won’t hurt you.

If I eat raspberries and mangos and lots of “sugary” fruits, am I actually eating a lot of sugar that I shouldn’t be? Are there certain fruits I should stay away from?

Consuming sugar in the form of fruit is better than consuming added sugar in the form of soft drinks, juices, processed foods and condiments but there can definitely be “too much” sugar consumed from fresh fruit alone. This depends on the overall balance of the rest of the diet, the overall caloric intake and the presence of underlying disease states in the individual consumer.

The FDA publishes a list of the nutrition content of raw fruits and vegetables so you can find out which fruits are higher in sugar contents than others, but truthfully we tend to under-consume fruits and vegetables so limiting your intake is probably not necessary.

What is important though is to focus on eating whole fruits and veggies (rather than processed forms, juices, etc.) to get all the nutritious benefits from them rather than just the sweet calories. And to choose whole fruits over other processed foods (like cookies and candy) when you are craving something sweet.


What percent of the diseases that you manage are linked to eating habits that revolve around sugar?

As a gastroenterologist, I take care of patients with digestive issues. What my patients put in their mouths has a huge affect on how their digestive systems work and how they feel (although occasionally it’s hard to prove this link).

Certain conditions (for example, irritable bowel syndrome) are more affected by sugar intake than others. I would say at least a third of my practice is managing patients with irritable bowel syndrome so we spend a significant amount of time focusing on dietary counseling and how to avoid foods (like certain sugars, among other types of foods) that might trigger or worsen symptoms.

What else is terrible for us?

The only thing that is worse to consume than sugar is artificial sweetener. These sugar substitutes (such as aspartame, sucralose and saccharine) are being linked to weight gain, obesity and metabolic syndrome. As more research is done on artificial sweeteners, I think we are bound to learn that there are even more detrimental effects from these additives than we realize. I’ve had people ask me (incredulously) that if they can’t drink soda, juice or artificial sweeteners, then what are they supposed to drink? I tell them “WATER.”

We should all be drinking more water!

What sort of diets do you recommend for your patients? (As in, animal protein = good? Bad?)

In general, I recommend a diet that is high in fiber and low in fat and comprised of whole foods (this macronutrient combination is linked with improved digestive health and even has been shown to reduce the risk of colorectal cancer).

Beyond that, I may make specific dietary recommendations based on a patient’s particular disease or symptoms although I try to work with the patient to find a diet that is realistic to his or her lifestyle. I practice in Portland, Oregon where there are great resources for people who want to follow specific dietary modifications but realistically people need to be able to adhere to the diet I recommend. So I try to be reasonable in my expectations of people.

How much sugar can I feel comfortable consuming daily?

Based on the most recent guidelines (2015-2020 Dietary Guidelines for Americans) the recommendation is to limit added sugars to no more than 10% of daily calories (based on a 1200-1800 calorie diet). The World Health Organization (WHO) just updated their guidelines to add a conditional recommendation to reduce added sugar intake to no more than 5% of daily caloric intake.

According to the WHO, “a conditional recommendation is one where the desirable effects of adhering to the recommendation probably outweigh the undesirable effects but these trade-offs need to be clarified.” I.e. more research needs to be done to know the right answer.

Is there a legitimate affect on the brain associated with sugar consumption?

The brain is an extremely energy-demanding organ so it requires a significant portion of the body’s glucose supply to function. That said, there is emerging evidence that there are detrimental affects of excess sugar (and certain types of sugar) on the brain. I’m not too familiar with this body of research, and much of the work has been done in animal models only thus far, but I bet if we stay tuned we are going to learn more about the effects of sugar on the brain and various disease states.

Are there any associated benefits at all with natural sugar consumption?

Of course! Sugar (in the form of glucose) is the most basic energy source for all the vital functions of our cells. We cannot survive without sugar!

How bad does this make alcohol for us?

Alcohol in moderation can still be OK. The current recommendation is no more than one drink per day for women and no more than two drinks per day for men. There are certain circumstances of course where alcohol should be avoided completely (you need to talk to your doctor to see if you fall into this category). But alcohol consumption can lead to excess sugar intake quickly especially if the alcohol is mixed with sugary mixers such as juice or soda. So all of those factors should be taken into consideration when drinking.

Do you recommend any sort of “hacks” to help your patients wean off sugar? Any foods that are sweet but not high in sugar?

I typically tell people that reducing their sugar intake is hard (sugar triggers reward centers in our brains just like other addictive things) but totally doable.

I recommend starting with low-hanging fruit (no pun intended) by cutting back on (and then eliminating) sugary beverages. I ask people to keep a food log of how much soda, juice, sweetened tea and coffee drinks they consume for a week. Usually people are totally stunned to see how much sugar they are drinking! Once they see where they are consuming most of their sugary calories, we can work to try to make realistic changes.

All of the research that has emerged in the last decade or so indicates that fat is not the devil, as you mentioned, but that it is sugar — can you explain to us what fat actually is and why we shouldn’t be afraid of it?

The story about fat is complex and rapidly evolving and a perfect example of why we shouldn’t vilify entire food groups completely. Dietary fat comes in multiple forms (trans fat, saturated fat, monounsaturated and polyunsaturated fat). The type of fat consumed is probably much more important than the total fat intake. The evidence is evolving rapidly about these different types of fat as we continue to learn more and more about them.

For now, we believe that trans fats should essentially be avoided and unsaturated fats should be chosen over saturated fats. Foods like fish, nuts and certain oils contain polyunsaturated fats that are believed to be healthier than saturated fats (like those found in red meat and dairy) but even saturated fats may be emerging as not quite as evil as once thought.

We will need to stay on top of this body of research to know where to go from here.

And finally! What are your top three food recs to live a hEaLThY life?

1. Eat whole foods rather than processed foods. The food you eat should be made of ‘ingredients’ not chemicals and additives.

2. Drink more water and less of everything else!

3. Learn to cook…if even a little. Cooking and preparing your own food will help you immensely at understanding and controlling what you are putting into your body.

So maybe sugar isn’t the new smoking after all. This is good news for me, who uses the entire industry that is movie theaters as an excuse to eat it in excess.

But mindfulness and moderation are key. Hmm, sounds familiar doesn’t it?

Sarah Diamond MD is an Assistant Professor of Medicine at Oregon Health and Science University in Portland, Oregon. She is board certified in gastroenterology and has an interest in nutrition and gastrointestinal motility. Interview conducted by Leandra Medine. Photographed by Krista Anna Lewis.


Get more Beauty ?
  • Kari

    This was such a great read! I found that once I stopped eating/drinking sugary foods I didn’t really crave them at all. I do however prompt remarks from most people regarding how much salt I put on my food, so..there’s that.
    I love her recommendation to learn how to cook! I do everyday. It’s so empowering to me to be able to make something delicious for myself and those I love, and you know exactly what you’re eating.

  • Mileena Hawks

    I currently profit in the range of 6-8 thousand dollars on monthly for freelancing i do from my home. Those who are looking to do basic online jobs for 2-5hrs every day from comfort of your home and make valuable paycheck while doing it… This is a job for you…Learn more about it here >


  • muiringue

    Good to see such a well-balanced article about this. I really liked the point about not vilifying whole food groups, but rather seeking balance and going back to food in its natural state more. There are some cool apps to help track sugar intake too – I’ve used one called Sugar Smart that scans barcodes so you can check before you buy. Sugar can be hidden in the weirdest of places. I stopped buying roast chicken breasts after I found out that they were cooked in a sugar marinade!

  • Kevlin Douchard

    I currently profit in the range of 6-8 thousand dollars on monthly for freelancing i do from my home. Those who are looking to do basic online jobs for 2-5hrs every day from comfort of your home and make valuable paycheck while doing it… This is a job for you…Learn more about it here >

  • Amelia Diamond

    Dr. Diamond bringing honor to the house since before I was born!

  • 808kate

    I work at OHSU too! (I’m a dietitian) — This was so fun to read!

  • Clara McKinnon

    Everything is okay in moderation everyone chill out and stop trying to cut out complete food groups. You can eat McDonald’s once in a while and still survive I promise

  • What are her favorite fiber rich foods?

  • Emma

    Love this. I think another important thing to note is that the chemical structure of different types of sugar makes it “better” and “worse” for us because of the way our body processes it and turns it into energy/fat and how slow or fast it’s metabolized. So agave nectar is mostly composed of fructose, which is not as good, even though its glycemic index is low, our bodies don’t really like it. And maple syrup has a different composition with less fructose, but it’s still sweet and yummy. (I heard it from Dr. Andrew Weil, my go-to guy for balanced diet advice–he looks to food to “heal” the body)

    So not to say you can only ever use maple syrup, but it’s one of those choices that feels more “stable” to me than even honey when I eat it, since I’m pretty sensitive to sugars!

  • ximena

    If you want to learn more about how food alters our body, you MUST read “Crazy Sexy Diet” by Kris Carr. It’s amazing and life changing 🙂

  • i have a question concerning decaf coffee, is it soooo bad ??

    • Leandra Medine

      i think so! but am also not a doctor. the thing is…you can’t like, GROW decaf beans, you know? so…how are they made if not in a lab