the last 10,000 years in response to radical changes in diet. in 2016, she was quoted as saying "it drives me crazy when paleo-diet people say that we've stopped evolving—we haven't". melvin konner has said the challenge to the hypothesis is not greatly significant since the real challenges to human non-adaptation have occurred with the rise of ever-more refined foodstuffs in the last 300 years. environmental impact a 2019 analysis of diets in the united states ranked consumption of a paleolithic diet as more environmentally harmful than consumption of an omnivorous diet, though not so harmful as a ketogenic diet. elizabeth kolbert has written the paleolithic diet's emphasis on meat consumption is a "disaster" on account of meat's comparatively high energy production costs. popularity a lifestyle and ideology have developed around the diet. "paleolithic" products include clothing, smartphone apps, and cookware. many paleolithic cookery books have been bestsellers. as of 2019 the market for products with the word "paleo" in their name was worth approximately $us500 million, with strong growth prospects despite pushback from the scientific community. some products were taking advantage of the trend by touting themselves as "paleo-approved" despite having no apparent link to the movement's tenets. like many other diets, the paleolithic diet is promoted by some by an appeal to nature and a narrative of conspiracy theories about how nutritional research, which does not support the supposed benefits of the paleolithic diet, is controlled by a malign food industry. paleolithic diet advocate john durant has blamed suppression of the truth about diet in the united states on "the vegetarian lobby".