What the calculator is doing (in plain English)

This tool has two jobs: (1) calculate your daily net calories (surplus or deficit), and (2) convert that daily number into a rough weekly/monthly projection. The “net” is simple subtraction:

If your net is negative, you’re in a deficit. If it’s positive, you’re in a surplus. If it’s close to zero, you’re near maintenance. The second part is turning that daily net into a projection. The classic rule of thumb says:

• ~3,500 kcal roughly equals 1 lb of body weight change
• ~7,700 kcal roughly equals 1 kg of body weight change

These numbers are simplified because your body adapts (metabolism, water balance, training changes), and because weight change can be a mix of fat, muscle, glycogen, and water. That’s why the calculator offers an “adaptive” option that slightly reduces projections at extremes.

If you don’t know your TDEE, full mode estimates it using a BMR formula (Mifflin-St Jeor) multiplied by an activity factor:

• BMR = 10×kg + 6.25×cm − 5×age + s (s = +5 male, −161 female)
• TDEE ≈ BMR × Activity factor

Best practice: once you use the estimate for 10–14 days, replace it with your real-world maintenance from tracking.

Examples (so you can sanity-check your result)

These are common scenarios. Your number may differ, but the logic will match. The goal is to see whether the result “feels” reasonable — and if not, adjust your inputs.

• Intake: 2,000 kcal/day
• Burned: 2,300 kcal/day
• Energy balance: −300 kcal/day (deficit)
• Projection (classic): about −0.6 lb/week

• Intake: 2,250 kcal/day
• Burned: 2,250 kcal/day
• Energy balance: ~0 kcal/day
• Projection: stable trend (normal fluctuations still happen)

• Intake: 2,800 kcal/day
• Burned: 2,400 kcal/day
• Energy balance: +400 kcal/day (surplus)
• Projection (classic): about +0.8 lb/week

If your scale weight moves faster in the first week, it may be water/glycogen, not pure fat or muscle.

How to use energy balance like a pro (without obsessing)

Energy balance becomes powerful when you treat it like a weekly experiment, not a daily judgment. Here’s a simple workflow that keeps you sane and gets results.

• Use a 7‑day average of intake (not one “good” day).
• Use a 7‑day average of scale weight (daily weight is noisy).

• If trend is flat for 2 weeks: change intake by 100–200 kcal/day.
• Hold the new number for 2 weeks before changing again.

• For fat loss, many people prefer a modest deficit that still supports training.
• For weight gain, a modest surplus usually looks better long-term than rushing.

• High-carb days can increase water weight quickly (glycogen storage).
• Stress, sleep, sodium, and soreness can swing weight day-to-day.

How to “create” a deficit or surplus easily

The easiest plan is one you can repeat. Here are simple tactics that work in real life. Pick one or two, not all of them.

• Protein anchor: include a protein source each meal to stay full.
• Volume foods: add fruits/veggies/soups to meals without many calories.
• Swap drinks: replace sugary drinks with zero-calorie options.
• Steps: adding daily walking helps without crushing appetite.

• Liquid calories: smoothies are easier than forcing huge meals.
• Calorie-dense add-ons: oils, nuts, nut butter, granola.
• Snack schedule: one planned snack daily can add 200–400 kcal reliably.
• Carb base: rice, oats, pasta, potatoes scale up easily.

Your best plan is the one that fits your schedule, appetite, and training.

When the projection doesn’t match reality

If your real trend is different than the calculator’s estimate, that doesn’t mean the calculator is “broken.” It means one of these is happening (and they’re all fixable).

• Under-tracking: oils, sauces, and snacks add up fast.
• Overestimating burned calories: fitness trackers can be optimistic.
• Water swings: carbs/sodium/stress can mask fat loss for a week.
• Metabolic adaptation: prolonged dieting can reduce energy expenditure.

• Keep intake consistent for 14 days.
• Track your 7‑day weight average.
• Adjust intake by ±150 kcal/day based on the trend direction you want.

Frequently Asked Questions

• What is “energy balance” in one sentence?

  It’s the difference between the calories you eat and the calories you burn — negative means deficit, positive means surplus.

• Do I need to count calories to use energy balance?

  Not forever. Many people count for 1–2 weeks to learn portions, then switch to “anchors” (repeatable meals + consistent snacks). The calculator is most useful when your inputs are consistent.

• Why does my scale weight fluctuate so much?

  Water, glycogen, sodium, sleep, stress, and soreness can swing weight day to day. That’s why the tool emphasizes weekly averages.

• Is 3,500 kcal per pound accurate?

  It’s a rough rule of thumb used for projections. Real bodies adapt, and weight change isn’t purely fat. Use it to set an initial plan, then adjust based on your 7‑day trend.

• What energy balance should I aim for?

  It depends on your goal and lifestyle. A modest deficit/surplus is often easier to sustain and tends to produce better-looking long-term results than extreme swings.

• What if I’m exercising but not losing weight?

  Exercise helps, but intake still matters. It’s common to eat more without noticing or overestimate calories burned. Try a 14‑day consistency test and adjust by 150 kcal/day based on your weight trend.