This is not medical advice. Everything below is general information for self-tracking. If you are under 18, pregnant or breastfeeding, have ever had a difficult relationship with food, or are managing a medical condition, speak to a doctor or a registered dietitian before you start counting anything. The full list of when to check first is here.
Does counting calories actually work?
Worth answering honestly before you spend a month on it. Calories are units of energy. Your body needs a certain amount every day just to keep running, and what you don't use gets stored.
The evidence for writing it down is better than the evidence for any particular diet. In the NIH-funded Weight Loss Maintenance trial, 1,685 overweight adults spent six months in a behavioural programme and lost a mean of 5.8 kg. When the researchers looked at who lost most, the behavioural measures explained most of the variation, and food records were the biggest of those.1 Worth noticing: participants managed 3.7 food records a week on average, not seven. Imperfect logging was the norm among the people it worked for.
A systematic review of 22 self-monitoring studies found the same association turning up again and again.2 The authors added a caveat you rarely see quoted alongside it: the level of evidence is weak, because the samples were mostly white women and adherence was almost always self-reported. The honest version, then, is that self-monitoring is reliably associated with losing more weight in the populations that have been studied. That is not quite the same claim as "calorie tracking makes you lose weight," and I'd rather give you the first one.
What that means for you: the value of logging is visibility, not precision. Most people are genuinely surprised by what their regular meals cost them, and you don't need a perfect record to get that surprise.
Step 1: find your calorie target
Your daily calorie need is called Total Daily Energy Expenditure, or TDEE. It's your basal metabolic rate multiplied by how much you move. Almost every reputable calorie calculator app estimates the BMR half with the Mifflin-St Jeor equation,3 which came out ahead of the alternatives when they were tested against measured metabolic rate.4 Our free calorie calculator runs it in your browser and gives you protein, carb and fat targets alongside it.
| Goal | Adjustment from TDEE | Roughly what to expect |
|---|---|---|
| Lose weight | 10% to 20% below | About 0.25 to 0.5 kg/week loss |
| Maintain weight | No change | Stable weight |
| Gain weight | 10% to 15% above | Slow gain, more of it lean |
Why a percentage, not a flat 500 calories
Most beginner guides tell you to subtract a flat 500 kcal a day. That comes from the old rule that 3,500 kcal is about a pound of fat, and it's a fine rule of thumb for an average-sized adult. It's a bad one for a small adult. A 500 kcal cut takes roughly 22% off a 2,300 kcal maintenance need and roughly 33% off a 1,500 kcal one. Same subtraction, very different diet.
So MyPlate scales the adjustment instead. A weight-loss goal lowers the target by 15%, a weight-gain goal raises it by 10%. Percentages have their own failure mode, though, and it's the one worth knowing about.
The floor matters more than the formula. A percentage deficit shrinks along with the person, so a small, older, sedentary profile can compute a target nobody should eat unsupervised. Put 40 kg / 150 cm / 60 years / female / lightly active / lose weight through the arithmetic and you get 1,024 kcal. MyPlate won't display that. No target ever drops below 1,200 kcal for women or 1,500 for men, following the NIH/NHLBI weight-management guidelines.5 If a calculator hands you a three-digit number without comment, distrust the calculator rather than your appetite.
None of this needs doing by hand. Any basic calorie counter app will take your details and compute the target for you. The thing to check in whichever one you pick is whether it recomputes later. In MyPlate the target gets rewritten when you change your goal or re-run your profile, but logging a new weight on its own won't move it. Re-run the setup every 4 to 6 kg and you'll stay roughly honest.
Step 2: know what you're actually eating
This is where most beginners come unstuck. You know you had "chicken and rice," but how much? The old answer was a kitchen scale and every gram logged. That's accurate, and it's why people quit in week two.
There are four ways to count calories in food, in rough order of effort. Read the label first: for anything packaged it's the most accurate source you will ever have, better than any database or scan, so use it whenever it exists. Failing that, estimate by hand size, a palm of protein, a cupped hand of carbs, a thumb of fat. It's crude but it takes no time and it travels. You can also search a food database directly. The USDA's FoodData Central6 is the reference set most apps are ultimately quoting, and it's free if you ever want to sanity-check a number one of them gave you. Last, photograph the plate and let a model estimate it. Fastest, least accurate, and I'll get to how much that matters in a moment.
In practice you mix them. Label when there is one, photo when there isn't, and don't agonise over the gap.
Step 3: let AI do the heavy lifting
Photographing a meal really is faster than searching for it. In MyPlate you open the app, tap the camera, take the photo (or type "chicken stir fry with vegetables and rice, about one plate"), and the estimate comes back with calories and the three macros already broken out. I built the MyPlate calorie tracker this way because searching a database is the step people abandon. Nobody ever quit over the arithmetic.
Is there such a thing as a most accurate calorie tracker?
Not really, and I'd rather say so than let you find out. A photo scan is an estimate, not a measurement, and three things move it that no camera can see.
The first is cooking fat. A tablespoon of oil in the pan is about 120 kcal and leaves no trace on the plate. It's the single biggest source of error in any photo-based estimate. The second is density below the surface: a model sees the top of a bowl, and whether the rice underneath is packed or loose is a 100 kcal question it can't answer. The third is anything hidden, so sugar in a sauce, butter through mashed potato, dressing already tossed into a salad.
MyPlate has no food database and no barcode scanner. Every estimate comes from the model reading a photo or a description, which is a deliberate limit on the design and worth knowing before you lean on it for anything clinical. If accuracy is what you're optimising for, the label on the packet beats every calorie counter app on the store, including mine.
Get more out of a scan: say what the photo can't show. "Chicken stir fry, cooked in about a tablespoon of oil, one plate" is a much better prompt than a bare photo, and it costs you five seconds. If a dish is mostly sauce, describe the sauce.
Does the error matter? For weight management, mostly not, as long as it's consistent. An estimate that runs 10% low every single day gives you a wrong number with a right trend, and the trend is the part you act on. Weigh yourself weekly, watch the direction over a month, and move the target if nothing is happening. That loop quietly corrects for a systematic error that no amount of careful logging would ever have caught.
Four mistakes that sink beginners
Tracking food but not drinks
Liquid calories are invisible to most people. A large latte, a glass of juice or a couple of beers can add 300 to 600 calories without ever registering as "food." Log everything you drink except plain water.
Forgetting cooking oils and condiments
A tablespoon of olive oil adds 120 calories. Salad dressing can add 150 to 300 more. These pile up fast, so log the sauces, the dressings and the cooking fats. A rough estimate still beats leaving them out.
Setting too aggressive a deficit
Cutting 1,000+ calories a day feels decisive and ends in hunger, fatigue and quitting. The NIH/NHLBI guidelines put sustainable loss at roughly 0.25 to 1 kg a week from a moderate deficit,5 and impatience doesn't change what your body gives up as fat rather than muscle. A 10 to 20% cut gets you there. A 40% cut gets you a fortnight of misery and a rebound.
Quitting after one bad day
You had pizza and didn't log it. Start again at the next meal, not next Monday and not after the holidays. Remember the trial above: the people who lost 5.8 kg were averaging 3.7 food records a week.1 Nobody in that study was logging perfectly.
Step 4: build the habit, not the obsession
You're not trying to become a human spreadsheet. You're trying to build enough awareness that you eventually don't need to track meals at all. That takes longer than most guides admit. The current systematic review of health-habit formation puts the median at around two months, and the spread between people is enormous.7 I've written separately about what the first four weeks realistically get you.
You'll know it's going well when logging a meal takes seconds rather than minutes and you don't dread opening the app, when you feel informed rather than restricted, and when your weight is drifting the right way across weeks rather than days. Being near your target most days without feeling deprived is the whole target.
And a limit. If tracking is making you anxious, if you're skipping meals to "save" calories, or if a number on a screen is deciding how you feel about yourself, stop and talk to a doctor or a registered dietitian. That isn't a failure of discipline and there is nothing an app can do about it. Put the tool down if the tool is hurting you. What the research says about who that is most likely to be is in can calorie tracking cause an eating disorder.
Common questions
Do I need to weigh my food?
No, and the evidence doesn't ask you to. Weighing improves accuracy, but what the literature associates with weight loss is consistent self-monitoring rather than precise self-monitoring.2 Weigh things for a week if you want the calibration. After that most people can eyeball the foods they eat regularly.
How long until I see results?
Weight moves day to day with water, salt and digestion, so one reading tells you almost nothing. Give it three or four weeks of weekly weigh-ins before you judge the trend. At a 10 to 20% deficit you're looking for roughly 0.25 to 0.5 kg a week, which is small enough to stay buried in the noise for the first fortnight.
What if my calculated target seems too low to live on?
Check it against the floor: 1,200 kcal for women, 1,500 for men.5 Anything below that belongs with a clinician rather than an app. If the number clears the floor and still feels punishing, you've probably overstated your deficit or understated your activity. Re-run the calculator honestly and try maintenance for a fortnight first.
Do I have to count macros too?
Not to lose weight. Calories decide the direction. Macros mostly decide how you feel getting there and how much muscle you keep. If you're going to track one thing beyond calories, make it protein, and here's why.
What should I look for in a calorie counter app?
Three things, and none of them are the feature list. Does it compute your target from a published formula, and will it tell you which one? Does it enforce a safety floor? And is logging fast enough that you'll still be doing it in week three? A simple calorie tracker app you open every day beats a sophisticated one you abandon. Everything else is preference.
Is a photo-based calorie counter accurate enough to trust?
For steering a weight trend, yes. For anything clinical, no: carb counting for diabetes, a renal or ketogenic protocol, any medically prescribed diet. Use labels and a dietitian's plan for those. Every estimate MyPlate produces is an approximation, which is why the sources page says so in plain terms.
The bottom line
Set a target from a real formula and check it against the floor. Log with whatever method you'll actually keep using. Assume the estimates are imperfect and let the weekly weight trend correct them for you. Assume the first month costs the most effort, because it does.
Ready to start? Download MyPlate and track your first meal today. No kitchen scale required.
Sources
Every figure above traces to one of these. If you find a number that doesn't match the source it claims, tell me and I'll correct it.
- Hollis JF, Gullion CM, Stevens VJ, et al. (2008). Weight loss during the intensive intervention phase of the weight-loss maintenance trial. American Journal of Preventive Medicine, 35(2):118-126. Read on PubMed →
- Burke LE, Wang J, Sevick MA (2011). Self-monitoring in weight loss: a systematic review of the literature. Journal of the American Dietetic Association, 111(1):92-102. Read on PubMed →
- Mifflin MD, St Jeor ST, Hill LA, Scott BJ, Daugherty SA, Koh YO (1990). A new predictive equation for resting energy expenditure in healthy individuals. American Journal of Clinical Nutrition, 51(2):241-247. Read on PubMed →
- Frankenfield D, Roth-Yousey L, Compher C (2005). Comparison of predictive equations for resting metabolic rate in healthy nonobese and obese adults. Journal of the American Dietetic Association, 105(5):775-789. Read on PubMed →
- National Heart, Lung, and Blood Institute, NIH (1998). Clinical Guidelines on the Identification, Evaluation, and Treatment of Overweight and Obesity in Adults. NIH Publication 98-4083. Read the guidelines →
- US Department of Agriculture, Agricultural Research Service. FoodData Central, reference composition data for foods. Open FoodData Central →
- Singh B, Murphy A, Maher C, Smith AE (2024). Time to form a habit: a systematic review and meta-analysis of health behaviour habit formation and its determinants. Healthcare, 12(23):2488. Read on PubMed →
The formulas and limits behind MyPlate's own numbers, with their citations, are on the health sources page.