Lean Groceries, Fat Savings: How I Hacked My Weekly Shop with the 80/20 Rule
Every time I do a food shop; I have two choices:
Walk into the store, grab what I need, and hope I’m not overpaying on things I could get cheaper elsewhere.
Be that person, the one who actually knows where to buy what, without wasting time or turning into a spreadsheet obsessive.
I choose option 2. Not because I’m obsessed with bargain hunting, but because I believe in leaning my life (small, repeat savings add up) , and that means building in effortless savings without overcomplicating the process.
80% of My Shopping is on Autopilot.
I don’t waste time comparing prices on everything. That would be exhausting. Instead, Lean Thinking loves a good 80/20. And here’s how it plays out in my weekly food shop:
80% of what I buy is consistent, routine and low-risk, the bread, milk, eggs, carrots, onions, salad, bananas… the kind of things where price swings aren’t dramatic and the mental effort to compare them isn’t worth the gain. That’s the autopilot zone. I know roughly what they cost across the five shops I use (Sainsbury’s, Tesco, Asda, Lidl, Aldi) and I don’t need to revisit those decisions weekly.
The other 20% are what I call my "runners and repeaters",
These are the sneaky ones like Brazil nuts, chia seeds, frozen strawberries, dried apricots, tahini, almond milk, you get the idea. Pantry items that come and go, but when they come, they sting. So instead of guessing or overpaying, I created a system.
The Price Check System (With a Lean Twist)
I only shop at a few places, just to make shopping more fun & less a chore. Sainsbury’s, Tesco, Asda, Lidl, Aldi, I don’t compare every store under the sun. Whenever I’m in one, I quickly check the price of my runners & repeaters and update a simple note on my phone. Not a spreadsheet. Not a complex database. Just a quick list of which store sells what, at the best price. And when I need to restock? I already know where to get it. No impulse buys. No checking prices aisle by aisle. No mental effort. Just effortless money-saving built into my normal shopping habits.
Let’s be honest, comparing grocery prices isn’t always easy. One store sells chia seeds at £2.49 for 200g. Another sells them at £3.99 for 350g. Another does a bulk buy 1kg bag at £6.50. Apples and pears. Or in this case, grams and litres. If you try to compare each product every time you shop, it quickly becomes more wasteful than helpful. So instead, I:
Do the price-per-kilo or per-litre calculation once,
Jot it into a simple note on my phone,
And use that to guide my decisions next time I shop.
No mental maths in the aisle. No second guessing. Just a simple reference built into my routine. And like any good Lean system, I run a little PDCA loop around it:
Plan → Add a few new “runner” items to track.
Do → Spot-check prices while I’m already in-store.
Check → Review any odd price changes or promotions.
Act → Update my note and adjust where I shop for it.
I don’t refresh prices every week, that would be overkill, but every couple of months, I’ll naturally pick up on changes when I notice price creep or seasonal shifts. This becomes part of my normal flow, when I see an item I know is one of my “repeaters,” I do a quick check without needing to hunt.
Shopping Smarter, Not Harder
Now, when I write my shopping list, I’m not starting from scratch. I plan based on:
Which store I’m already visiting
Which “runner” items are due a restock
Which prices I know give me the best value
It means I don’t waste time trying to be perfect. I just make informed, good-enough decisions that save money without extra stress. This is built into my routine now, not a separate project. It doesn’t take effort, it removes effort.
Why This Works (And Why Most People Don’t Do It) Most people either:
Stick to one store and overpay
Or try to be hyper-efficient and end up spending more time than they save
Lean Thinking gives me the sweet spot:
Enough structure to eliminate guesswork
Just enough flexibility to adapt as things change
No unnecessary motion, time, or mental clutter
And this system isn’t just limited to food. Here are two other ways I apply the same logic:
Toiletries – I know my go-to catsand is £2.30 cheaper in Asda than Sainsbury’s. So, if I’m doing an Asda run, I stock up when necessary.
Supplements – My go-to magnesium tablets are often on a 3-for-2 deal at Holland & Barrett, in Tesco, so I only top up when that deal is on, and skip it the rest of the time.
Again, not obsessive, just conscious. My approach? Lean and practical.
I don’t go out of my way; I only check prices when I’m in those stores anyway.
I don’t track everything, just the things where price swings are worth it.
I don’t stress about change, prices fluctuate, but over time, patterns emerge.
The goal isn’t to micromanage spending, it’s to automate smart shopping decisions so that saving money takes zero extra effort.
Now, when I write my shopping list, I don’t waste time wondering where to buy what. If I’m going to Aldi, I know exactly which pantry staples to stock up on. If I’m passing Tesco, I grab the things they weirdly sell cheaper than anywhere else. If I need Brazil nuts, I already know which store doesn’t price them like gold bars. A simple system that eliminates pointless decisions, saves pennies without chasing them, and makes food shopping as Lean as it gets.
Your Turn: What’s Your Grocery Lean Hack?
What do you find yourself repeatedly overpaying for, forgetting the price of, or hesitating over?
Do you have your own shopping cheat sheet? Do you mentally calculate prices or wing it based on what feels right? Do you do what most people do, and hope for the best?
Drop a comment, I’d love to hear it!
