Get Dr. Bobby's 1-page summary of this episode

Sugar is toxic. Carbs spike insulin. White bread is bad. Pasta makes us fat.

But how much of that is actually supported by evidence?

In this episode of Live Long and Well, I take a second look at the “forbidden food” problem.

In an earlier episode, we examined salt and found that population advice does not always translate into the same rule for every individual.

Now we ask the same question about sugar and carbohydrates.

In people with diabetes, chronically elevated glucose clearly causes harm. Both UKPDS in type 2 diabetes and the DCCT in type 1 diabetes showed that better glucose control reduces important complications. But that does not establish that every normal glucose rise after a meal is harmful in someone without diabetes.

We also look at whether sugar is uniquely fattening. A BMJ systematic review found that changing sugar intake affected weight when calories changed, but exchanging sugar calorie-for-calorie with other carbohydrates produced essentially no difference in weight.

Then there is the brownie: sugar, refined flour, fat and lots of calories. A meta-analysis involving more than 875,000 people found no significant overall association between refined-grain intake and cardiovascular disease, stroke or heart failure.

Bread and pasta get similar scrutiny. A meta-analysis of randomized pasta trials found no evidence that pasta, when eaten as part of lower-glycemic dietary patterns, promoted weight gain.

Whole grains probably have some advantages, but the difference may be more modest than nutrition rules sometimes imply. A review of randomized trials comparing whole and refined grains found modest improvements in several cardiovascular risk factors with whole grains.

We also discuss why oatmeal, lentils, soda and brownies can all be called “carbohydrates” even though they are very different foods; what my own continuous glucose monitor has taught me; why a post-meal walk can reduce the glucose excursion; and why rapidly absorbed carbohydrate can be useful fuel during prolonged endurance exercise.

The central question is not simply whether a food is good or bad.

It is: for whom, how much, how often, and in what context?

If you have diabetes or prediabetes, glucose control matters and deserves individualized medical guidance.

But for many metabolically healthy people, the evidence does not support treating an occasional brownie, a pasta dinner or a piece of white bread as a metabolic catastrophe.

Whole grains may be somewhat better.

That does not make everything else forbidden.

The goal is not nutritional perfection.

It is to live long—and preserve our joy span while doing it.

Send us Fan Mail

Support the show