Global food demand surges with population growth and richer middle class craving meat. Rich world exceeds healthy meat limit of 26kg per person yearly. More humans now overweight than underweight shifting hunger to obesity crisis. Food systems cause nearly a third of greenhouse emissions mainly from meat. Decarbonizing demands slashing meat production. Poor face higher costs for nutritious diets versus calorie-dense junk. Commodity crops like maize and soy dominate cheap calories but harm soil and biodiversity. Future diets trend toward veggies, whole grains, less sugar and fried foods. Meat becomes occasional treat not daily staple. Ultra-processed foods get reformulated for nutrients not excess calories. Rich-poor food divide blurs with global trade and local production. Food waste fills landfills in overeating regions. Big agriculture efficiencies enable gluttony but kill jobs and nature. Sustainable nutrition requires contract-and-converge model. Poor need affordable healthy culturally fit diets.