I came across this yesterday and thought it was worth sharing. The speaker is not a crank trying to sell you a new food religion or a diet plan: he's an insider in the food industry. It's quite hard to summarize his theme and still do it justice, so do watch. It's only 12 minutes. If you find your curiosity piqued, you can go as far down this rabbithole as you like - a lot has been written and said about it.
He's referring to the American food landscape, but the UK isn't radically different.
If there's any single takeaway from the video it's this: the food giants simply want to sell you stuff. They don't care if it makes you fat and ill, as long as you buy lots of their products before you die. They'll tell you their products are healthy and wholesome in order to achieve this, but mostly they're not. So cook for yourself. Make stuff yourself. Grow your own if you're up to it. You'll feel better for it.