I kept logging meals and getting a number back. 1,840 of 2,300 calories. Useful, but it never told me what I actually wanted to know: What is my body doing with the food I already ate? Am I still running through lunch? Have I burned through most of my available glycogen? Am I shifting toward using more body fat? And most importantly: Does my body actually need more fuel right now, or am I eating simply because it is “time to eat”? So I built what I wanted. Fuel Shift changes the way you think about eating. Instead of seeing food as breakfast, lunch, dinner, snacks, and calories, you start seeing it for what it really is: Fuel. You begin thinking less about the act of eating and more about refueling your body when it actually makes sense to refuel. Fuel Shift models four major places your body stores and uses energy: Glucose in your bloodstream. Glycogen in your liver. Glycogen in your muscles. Body fat. Log your meals and workouts like you normally would, and Fuel Shift simulates forward from there. The dashboard lets you watch those energy stores fill and drain, see the estimated fuel mix your body is using right now, and see how long it may take before your body begins relying more heavily on stored fat. That changes the question from: “How many calories do I have left today?” to: “What does my body actually need right now?” And once you start seeing food this way, your relationship with eating begins to shift. You start understanding why eating at certain times makes sense, why sometimes waiting makes sense, how a workout changes your fuel state, and what happens when you eat again before your body has finished working through the energy you already gave it. The model is the product, not decoration. Gut absorption, hepatic first pass, insulin response, obligate glucose use, glycogen utilization, and the way muscle glycogen is conserved differently during fasting are all incorporated into the simulation, with sources behind the assumptions and a self-test suite that checks model behavior against published physiology. Muscle glycogen even has its own tank because muscle cannot simply release its stored glucose back into the bloodstream the way the liver can. The two stores behave very differently, so Fuel Shift treats them differently. There is also a What If mode. Before you eat something, enter the meal. Fuel Shift forks the simulation into two futures: One where you eat it. One where you don't. Then it estimates what changes. How much energy is likely replenishing glycogen? How much is being used? How much could be stored? How does the meal change your fuel mix? And how much longer might it take before your body shifts back toward greater fat utilization? For the first time, you can actually see the potential metabolic consequence of a meal before deciding whether to eat it. Fuel Shift does not pretend it can override energy balance. If your goal is fat loss, total energy intake still matters enormously, and Fuel Shift tells you that plainly. This isn't magic. It is about timing, awareness, and understanding. Instead of guessing when to eat, guessing whether you need fuel, or staring at a calorie number with no context, you can begin to understand what may be happening inside your body. Stop thinking only about eating. Start thinking about refueling. Seven-day free trial. No credit card required. Especially interested in hearing from people who fast, train fasted, or have ever wondered: “What is my body actually burning right now?”

Fuel Shift

See the moment your body switches to burning fat

See the moment your body switches to burning fat