Whatever diet you follow — Akins or Ornish, Dukan or DASH — here’s one piece of advice they’ll likely have in common: skip the French fries. Fried potatoes – and other fried foods – are widely regarded as among the most notorious of nutritional villains. That notoriety is also key to a new effort to make a healthier French fry with 40% less fat and 30% fewer calories than the average fried spud.
But do fried foods really deserve the bad rap? The answer is: not necessarily.
Surprisingly, the evidence tying fried foods to health problems is mixed. While some research has linked fried foods to obesity, heart attacks, and diabetes, a recent long-term study of more than 40,000 Spanish adults found that those who ate the most fried foods had no greater risk of heart disease or premature death. Another study, this one in obese women, even found a beneficial effect of fried foods on insulin levels.
One possible reason for the inconsistent findings is that studies varied in the types of oils or fats used for frying. Participants in the Spanish study used mainly olive and sunflower oils, and those in the study showing a benefit ate food fried in extra-virgin olive oil. In contrast, people in other research may have used frying substances that are more prone to break down into harmful trans fats.
The type of oil or fat is just one factor that can affect the healthfulness of a fried food. Other possibilities include how it’s fried (deep or pan), whether the oil is reused (the less, the better), and how much salt is added.
The effects of frying on food are complex, and there’s much scientists still don’t fully understand. Which leads to whether a better-for-you French fry is really possible. In theory, it is – but that would require further research to determine how various oils, frying methods, and other factors affect health outcomes. In the meantime, any claims are largely a guess.
What we do know from research is that it’s your overall dietary pattern that matters. Even the most healthful fries, when consumed as part of a diet dominated by processed and fast food, aren’t going to do you much good. On the other hand, the greasiest fried foods, when eaten occasionally as part of an otherwise healthful diet, aren’t going to kill you.
Read more about TIME’s taste test of the healthier fry here.