Sugar

The cake tastes sweet without much glucose and sucrose because it has lots of HFCS.

Oh, HFCS stands for high fructose corn syrup - a common sweetener we use in bakery and soft drinks, and a classical story of how (pseudo)science could pull our own legs ...

Many decades ago, people began to realize ordinary sugar - glucose and sucrose -could increase blood glucose level, and is probably no good for large scale public use. (Diabetes was a big name !) The search for a natural sweetener that would not rise blood glucose level (that much) eventually gives the answer fructose - which comes from fruits and vegetables, is equally sweet as glucose, and the final product has a long shelf life. That's how HFCS came along.

Yes, it remains controversial how much does HFCS contribute to the epidemics of obesity and insulin resistance. Nonetheless, everything sweet has a cost (alas, contains calorie if not carcinogen), and the fat you get remain the same no matter what's written on the label.