The parties who had a financial or reputational interest in concealing evidence that cigarettes cause cancer: Tobacco companies, tobacco farmers, tobacco retailers. Those with an interest in concealing the role of carbohydrates in our modern day obesity and diabetes epidemic:
Makers and sellers of extra large clothes, mobility scooter makers, hospitals, diet drug sellers, weight watchers, heart medicine sellers, the beer industry, body positive advocates, anyone who claims to have a "slow metabolism", and possibly your mom.