The science behind controversial ‘health’ foods
1. Fruit
Let me start by saying I don’t think fruit is bad for your health. If you’re choosing between a Twinkie and an apple, by all means, choose the apple.
But the truth is that fruit today isn’t as nutritionally dense as it was a few generations ago. Fruit is also much sweeter than it used to be and not necessarily good for blood sugar management.
Let’s look at the facts:
- Since the Plant Patent Act of 1930, farmers have been incentivized to create the sweetest, fattest, most seedless fruit varieties possible.
- Studies show modern plant varieties are much sweeter than older cultivars due to decades of continuous breeding and selection.
- Fruits such as apples are softer and sweeter than they were in the 1970s.
- Even zoos stopped feeding modern fruits to their animals — the baseline sugar content could be dangerous to their health.
The side effect of this is sweeter fruit that’s dangerously low in nutrients. Research shows you’d have to consume eight oranges to get the same amount of vitamin A your grandparents did.
Now imagine eating all this sugar in an unbalanced diet. To put it in perspective, a single mango contains 46 grams of sugar. A 12-ounce can of Coca-Cola has just 39 grams of sugar.
Again, I’m not saying fruit is worse than processed drinks. I’m also not telling you to completely abandon your favorite fruits. Fruit, especially as a garnish, is fine if you’re metabolically healthy.
But as you’ve seen, large amounts of certain fruits aren’t necessarily good for your blood sugar. If you’re a diabetic, a recovering food addict, or someone fighting metabolic syndrome, moderation is key.
The good news is, there are a few fruits that (usually) won’t impact your insulin. Berries, watermelons, and avocados are among the most popular.
But again, everyone’s body reacts differently to different foods. The only way to be sure is to get a continuous glucose monitor, which tracks blood sugar levels throughout the day.
2. Fiber
I’m sure you grew up hearing that fiber is an essential dietary nutrient. You’ve probably seen most of this advertised on cereal boxes, instant oatmeal, and granola bars.
But despite the memorable catch phrases like ‘heart-healthy’ and ‘part of this complete breakfast,’ dietary fiber isn’t the ‘must-have’ you’ve been led to believe.
Let me give you the Sparknotes:
- Fiber is a type of carbohydrate. Humans don’t need carbohydrates to function effectively (and certainly not 75% of our daily calories).
- Studies show fiber is incompatible to the digestive tract. It’s also bulky and abrasive, which worsens chronic disease like IBS.
- Contrary to popular belief, fiber may also hinder digestion. Some research suggests it could reduce fertility — but you probably won’t see that on the Quaker Oats container.
However, high-fiber advocates are right in some respects. If you’re eating tons of processed food, you’re going to need something to clear out the waste. Fiber is the obvious choice for this. So if you’re eating the Standard American Diet, you’d better be eating plenty of fiber!
I’m not advocating a no-fiber diet. However, eating Cheerios just to reach your daily fiber intake is as bad as taking statins to ‘stop’ heart disease.
And remember: a low-carb diet is not necessarily a low fiber diet. Dr. Zoë Harcombe has an excellent video on the subject.
3. Diet beverages
Since the first sugar-free drink released in 1952, diet sodas have become a staple of American diet culture. Approximately one in four sodas purchased today are considered ‘diet’ drinks.
Will you lose weight drinking diet soda? Maybe, if you drank a lot before then.
But will diet soda make you healthier? Absolutely not.
If anything, it will only make you sicker:
- Regularly drinking diet soda leads to chronic illnesses and heart disease.
- You have a higher risk of metabolic syndrome, even though there’s no ‘real sugar’ in a diet drink.
- The artificial sugars in diet soda have a direct correlation to cancer.
Quitting a soda habit can feel just as hard as quitting an alcohol habit, so don’t try to give it up all at once. The better approach is to wean yourself off by replacing your habit with a better one (like lemon water).
4. Low-fat yogurt
I’ve written a lot about the low-fat lie before, but in this case, it bears repeating again.
Low-fat foods will not reduce your risks of a heart attack. But they can cause you to feel hungry all the time, which encourages you to eat more in response.
I’ll let the risks speak for themselves:
- Low-fat yogurt may increase your risk for prediabetes.
- It can also spike your insulin — some brands come with 29 grams of sugar per serving.
- Low-fat yogurt is heavily processed. Heavily-processed foods are associated with all-cause mortality and worse heart health overall.
It may be true that low-fat yogurt has fewer calories than full-fat, but keep in mind metabolic health isn’t a calories-in-calories-out game. Satiety and nutrient-density are essential to restoring your health: something low-fat yogurt isn’t going to provide.
If you want to keep yogurt in your diet, opt for full-fat, plain flavors instead. This is less likely to contain sugar, which only adds more stress to your body’s insulin response.
Remember: ‘low fat’ does not mean ‘won’t make you fat.’ If anything, it’s the exact opposite.
5. ‘Healthy’ sugar
Humans have consumed sweeteners for thousands of years. But what we haven’t consumed for long is processed sugar, which is mechanically manipulated and nutritionally devoid.
Pick up any item in the center aisle of your grocery store, and I’m willing to bet it has added sugar. As many as 60% of our foods and beverages contain added sugar, and usually not an unprocessed kind.
Some companies have tried to pivot to the health-conscious by producing ‘healthier’ sugar alternatives. This includes artificial sugars like aspartame, sucralose, and acesulfame, all of which contribute to chronic disease.
So is there such a thing as healthy sugar? Not necessarily. But there is a sliding scale of processing ranging from ultra-processed to naturally derived:
- Highly processed sugar like high fructose corn syrup is barely real food and should be avoided.
- Extracts like stevia aren’t quite as bad, though you do need to buy from a quality brand.
- Lightly processed sweeteners like date syrup and maple syrup can spike your blood sugar but still come from whole, real foods.
- Raw honey is the least processed and most nutritionally dense sweetener. Just be sure you’re buying a local variety and not an artificially processed ‘honey alternative.’
I won’t say sweeteners are good for you here. But if you’re metabolically healthy, you’re unlikely to have side effects.
That said, the vast majority of Americans aren’t metabolically healthy, which means even a small amount of sugar can imbalance satiety hormones, blood sugar levels, and insulin response.
Proceed with caution.
So what diet should you follow instead?
I never demand my patients follow particular diets. My role as a physician is to educate and instruct.
All that said, I’m not shy about providing guidelines.
Here’s how to find (and eat) truly healthy foods:
- Focus on purchasing whole, real foods. This includes anything that comes from the ground or eats food on the ground. Cabbages, cows, and coconuts are just a few of these. Notice most of these don’t have an ingredients list (unless they’re prewashed or prepackaged).
- If you do buy food with an ingredients list, know how to tell the acceptable from the unacceptable. You should never buy ingredients you don’t understand and avoid unhealthy additives like sugar, vegetable oil, and food dye.
- Get a continuous glucose monitor. You can use this to measure the impact of certain foods and make better decisions about what works (and what doesn’t) for your body.
If you’re looking to learn more about eating for better metabolic health, I’ve filmed several resources you can reference along your journey.
And if you’d like to speak with one of my metabolic coaches, you’re welcome to reach out to my metabolic health coordinator.
