About Vincent Ooi
Vincent builds the apps because he uses them. He is the founder of DaSecure and the developer behind FastFlow, an iOS fasting tracker that reads Garmin and Apple Watch biometrics live, and DaInterval Pro, a Garmin Connect IQ app that guides Zone 2 training with haptic alerts. In his 60s, he fasts regularly and puts most of his training volume in Zone 2 - so every feature ships only after it has survived his own fasts and his own runs.
That order matters. FastFlow didn't start as a business plan; it started as a question Vincent kept asking his own watch: what is actually happening in my body right now? A countdown timer couldn't answer it. His Garmin was already recording heart rate, HRV, Body Battery and stress - the physiological story of every fast - but nothing connected that data to the fast itself. So he built the connection: a BLE link between the watch and the phone, and a plain-language map of the six metabolic stages. DaInterval came the same way, from wanting to hold an easy aerobic pace on the trail without staring at a screen every thirty seconds.
What he believes
The thread through everything is an old Daoist idea: Wu Wei - effortless action, working with the current instead of thrashing against it. Applied to health after 40, it means working with the body's natural intelligence rather than grinding against it. Fasting is not willpower; it's letting a metabolic system do what it already knows how to do. Zone 2 is not punishment; it's the pace your aerobic engine was built for. The body wants to heal, adapt and endure. The work is mostly getting out of its way.
That's why the apps are deliberately quiet. No streaks to defend, no leaderboards, no gamified guilt. FastFlow has no account and no servers holding your health data; DaInterval buzzes only when you drift out of your zone. Tools you set once and mostly ignore - the opposite of hustle culture, which Vincent thinks has no business anywhere near longevity. Consistency over decades beats intensity over weeks, and consistency is only possible when the practice is calm enough to keep.
The engineering background
DaSecure is Vincent's software company, and the wearable link is its specialty: native Garmin Connect IQ development, iOS development, and the unglamorous BLE plumbing that lets a watch stream live sensor data to a phone. It's the hard part most fasting apps skipped, and it's the foundation both products stand on.
Why the writing here is honest
The guides and comparisons on this site follow one rule: balanced beats hype. Where a free Connect IQ widget is the smarter choice, the articles say so. Where Zero's education library or Simple's coaching beats FastFlow, the comparisons say that too. Vincent is 60+ and fasting and training alongside the people he builds for - recommending the wrong tool to that audience would be pointless.
You can follow along at @vooi and @fastflowapp on Instagram, or @fastflow65 on TikTok - or just start with the definitive guide to fasting on a Garmin and the Zone 2 calculator.