The law in South Africa says that short-term health insurers can't charge different people different premiums, so this is an 'add-on cashback scheme'.
They integrate with 2 big supermarket chains: when you pay with a credit card issued by the insurer's banking partner, your discounts are automatically processed on a line-by-line product level. They also integrate with a fast food chain in the same way, Nandos, and give you a discount for selecting the 'healthier' food choices on the menu.
[1] https://www.discovery.co.za/vitality/help-healthyfood-health...