There is no single “best” cooking method for every food, because health outcomes depend on what you cook and what heat does to it. In general, gentler methods (like steaming, microwaving with minimal water, and baking at moderate temperatures) often protect more of a vegetable’s beneficial compounds than boiling for long periods.

Research on vegetables shows that cooking can change total phenolics and antioxidant activity, but not always in a negative way: depending on the vegetable, antioxidant activity may increase or stay similar after cooking. However, studies comparing home methods often find that boiling and pressure-cooking can cause larger losses in some antioxidant measures, largely because nutrients can leach into the cooking water.

For vegetables, the “healthiest” trend is to use methods that limit water loss and overcooking. Microwaving (with little water), griddling, and baking often produce smaller antioxidant losses than boiling, while frying sits in the middle. Steaming tends to behave like a water-sparing method in practice (even though it isn’t directly tested in every study), because food is not submerged and fewer water-soluble compounds are washed away. The key is time: shorter cooking preserves more, while softening can also improve palatability and make some compounds easier to access.

For starchy foods like potatoes, high dry heat can create acrylamide, a compound linked to the Maillard reaction—especially when foods rich in asparagine and sugars are heated intensely (frying is a common example). For meats, very high-temperature cooking (especially well-done, charred, or heavily browned meat) can produce heterocyclic amines (HCAs) and polycyclic aromatic hydrocarbons (PAHs). Large studies linking cooking patterns to health outcomes have found that well-done red meat and higher estimated exposure to certain HCAs/PAHs are associated with higher colorectal adenoma risk.

Modern kitchen gadgets can help—but only if they guide you toward better heat control. Air fryers can reduce the need for added oil compared with deep frying, but reviews note that air frying can create a pro-oxidative environment for lipids, with evidence of oxidation products and degradation of sensitive fats (especially in fish). So “modern” is not automatically “healthier”; the healthiest tool is the one that helps you cook with less charring, less oil overload, and better temperature control.