The well-known "21 days" figure is not what the research shows. In a real-world study of daily habits, it took people a median of 66 days for a new behavior to feel automatic, with a wide range from about 18 days to well over 200. Missing a single day did not undo the process, which is good news for anyone starting over.

Many store receipts are printed on thermal paper that has used BPA or similar chemicals as the developer. A 2014 study found that holding thermal receipts right after using hand sanitizer and then eating finger food led to a quick rise in BPA levels in the blood and urine. Saying no to paper receipts, or keeping them away from freshly sanitized hands and food, is an easy change.

Heating food in plastic is one of the easier everyday exposures to change. A 2023 lab study found that microwaving plastic food containers released far more micro- and nanoplastic particles into the food than storing food in them at room temperature or in the fridge. Moving leftovers into glass or ceramic before you heat them is a simple swap.

A few simple habits can lower the plastic particles in the water you drink. Researchers have counted very large numbers of tiny plastic particles in bottled water, so choosing filtered tap water in a glass or stainless steel bottle is a practical first step. One lab study also found that boiling hard tap water and then pouring it through a basic filter removed much of the plastic it tested.

A randomized Stanford study found that building up to about six servings of fermented foods a day raised gut diversity and lowered several blood inflammation markers. Here is what it showed and what it did not.

How to take L-theanine: NOW Foods label dosing (1 capsule 1 to 2 times daily), 100 mg vs 200 mg, morning vs night, taking it with coffee, magnesium, melatonin, or ashwagandha, and cautions.

ApoB counts the particles that can carry cholesterol into the artery wall. Here is what large genetic and cohort studies show about apoB compared with LDL cholesterol.

VO2 max measures how well your body uses oxygen, and large studies link higher fitness with lower risk of death from any cause. Here is what the research shows and how fitness can be built.

How to take Pendulum Akkermansia: label dosing of 1 capsule daily with food and 8 oz of water, refrigeration, what is in it (Akkermansia muciniphila WB-STR-0001 plus inulin), and cautions.

How to take Sunfiber (partially hydrolyzed guar gum): label dosing of one 7 g scoop in 6 to 8 oz of a non-carbonated drink, when to take it, and how to start slowly.