How to Pick a Weight Loss App You Will Keep Using

The weight loss app worth keeping makes logging quick, refuses goals below a safe floor, and never promises more than the usual pace of 0.5–1 kg (1–2 lb) a week. I’d ignore the rest. This guide gives you an eight-point checklist and the evidence behind each point, starting with the NHS pace.

What does an app for weight loss actually do?

It keeps a food diary, a goal and a weight trend in one place. That’s all. The research behind these apps is research on self-monitoring. A systematic review of 22 studies, 15 of them on diet, consistently found a significant link between self-monitoring and weight loss. It also rated the evidence weak, because the samples were mostly white women and the studies relied on self-report.

A link isn’t proof that logging causes weight loss, so I use an app to hold the habit in place and expect nothing more from it.

So judge an app by what it does on a bad day, when you skip a log or eat far more than planned.

Your weight moves from day to day, so one morning’s number tells you little. A smoothed trend lets you look at a week instead, and the weight loss tracker app post shows how to read it.

How fast should a weight loss app say I can lose?

No faster than the usual pace. The NHS says to aim for 1–2 lb, or 0.5–1 kg, a week, and the CDC describes a gradual, steady pace of about 1 to 2 pounds a week. Start at the low end, since half a kilo is the safer default and 2 lb is the most you should plan on.

The energy side has a published range too. The 2013 AHA/ACC/TOS guideline lists usual weight-loss targets of 1,200 kcal to 1,500 kcal a day for women and 1,500 kcal to 1,800 kcal for men, adjusted to body weight and activity. So 1,200 and 1,500 are the bottoms of those ranges. An app that lets you type 900 kcal, or hides the warning behind a tap, has no safe floor.

On average, says the NHS, women use around 2,000 calories a day and men 2,500. Averages hide a lot. Someone who uses more than that gets a higher goal at the same pace, which is why an app should ask about you first and not hand everyone one number.

Any goal calculator starts from averages, so expect it to be off for you by some margin. Give it a few weeks of weigh-ins before you judge it, then change the goal in small steps instead of cutting harder.

Watch for dates. An app that promises a weight by a holiday or a wedding is promising more than the NHS or CDC pace allows. If one app shows a finish date and another shows none, the one with no date is being straighter with you.

The weekly range describes a good week, and the long run is slower. The same guideline recommends an initial goal of 5%–10% of baseline weight within 6 months. For an 80 kg adult that is 4–8 kg, or about 0.15–0.3 kg a week averaged over 26 weeks. A forecast that repeats 0.5 kg every week for half a year shows 13 kg, which is 16% of 80 kg. Hall and colleagues’ 2011 model explains why real lines bend: body weight responds slowly to a change in intake, with half times of about a year. Look at what your app’s forecast does after the first month. A line that stays straight for six months is a promise.

If you take medication, are pregnant or have a health condition, your calorie goal is a conversation with your doctor, not an app setting. This guide is for adults.

How do I check the calorie goal an app gives me?

Rebuild it from two public numbers and see whether the app lands close. The NHS lists 2,000 calories a day for women and 2,500 for men as recommended daily averages. It also says to find about 600 calories to cut from your usual day.

Take the woman’s average first. 2,000 minus 600 is 1,400 kcal, which sits inside the 1,200–1,500 kcal range from the AHA/ACC/TOS guideline above. For the man’s average, 2,500 minus 600 is 1,900 kcal, above that guideline’s 1,500–1,800 range. Nothing is wrong there. The guideline adjusts its levels to body weight, so 1,900 for a larger, more active man breaks no rule.

Now check the pace. A 600 kcal gap held for seven days is 4,200 kcal. The old rule counts a pound of body weight as 3,500 kcal. Hall’s 2008 analysis gives that as 32.2 MJ per kilogram, or about 7,700 kcal. Divide 4,200 by 7,700 and you get roughly 0.55 kg (1.2 lb) a week, the bottom of the NHS range. Those two NHS figures line up, so a goal near 1,400 kcal fits that woman.

Treat 0.55 kg as a ceiling for the first weeks. Thomas and colleagues tested the rule against seven weight loss experiments with supervised or measured intake. They describe it as one that grossly overestimates actual loss.

Then run three tests on the app itself:

1. Enter your real age, height, weight and activity. Write down the maintenance figure it shows and compare it with the NHS averages above.
2. Change one input at a time, such as activity, and watch the goal move the right way.
3. Pick the fastest pace on offer. A sound app stops at the usual pace or warns you, and shows no finish date.

For a number outside any app, the calorie calculator runs the NASEM 2023 equations and never sets a target below 1,200 or 1,500 kcal. If it and the app disagree, start with the calculator’s figure and let two weeks of your own weigh-ins decide.

Will I keep using it?

Logging effort fades. In a 24-week online program, 142 adults who logged their food spent 23.2 minutes a day in month 1 and 14.6 minutes in month 6. Only 65.5% were still recording at month 6. Those who lost 5% or more of their weight opened the journal 2.4 times a day, against 1.6 for those who lost less. Take that as an association only.

Test speed first. Log your usual breakfast and count the taps.

Then check how the app treats a day off. 8 of the 15 trackers I checked use streaks or rewards, which make a day off look like a loss. You want an app where a break costs nothing and the diary is still there when you return. If an app’s store text promises no calorie counting at all, the simple app weight loss review shows what its free version allows and what stays behind Premium.

Does an app keep me logging longer than a paper diary?

One pilot says it can. In a 6-month trial with 128 volunteers, 93% of the smartphone group was still taking part at the end, against 53% of the paper-diary group. The app group recorded food on a mean of 92 days, and the diary group on 29.

The app in that trial was built by the research team, so it tells you nothing about the one on your phone. The format helps, but the pilot ran only six months.

What makes a diary wrong even when I log every day?

Memory. A lab study followed ten people who said they ate under 1,200 kcal a day and were not losing weight. Measured over two weeks, they had under-reported their food by 47% on average and over-reported their exercise by 51%. Ten people picked for a history of failing to lose weight cannot describe everyone.

The OPEN study of 484 adults found the same direction at a smaller size. On 24-hour recalls, men under-reported energy intake by 12–14% and women by 16–20%.

Both studies tested recall. Neither tested an app. An app helps only if you log at the table, with the food in front of you and the grams measured. In my own diary, cooking oil is the entry I forget first, and a tablespoon of olive oil is 119 kcal. I would weigh the oil first.

What should I check before I pay or share my data?

The paywall and the privacy box, in that order. In the same check, 13 of the 15 apps asked their questions before they showed a price, and 7 used a countdown timer, a discount wheel or a second offer. 10 had a free tier, and 13 declared tracking on their App Store page.

A free tier can be enough. What matters is what it leaves out, and whether you can leave. The NHS weight loss app is a free 12-week plan with a calorie diary and no barcode scanner, a fair example of a gap you may accept. Read the cancel route before you subscribe, and look for an export button, because your diary is yours.

I boil it down to eight points, and the longer ten-test version lives in how to choose a calorie counter app.

1. You can log a meal you eat often in under a minute.
2. The calorie goal can’t go below 1,200 kcal for women or 1,500 kcal for men.
3. The pace defaults to half a kilo a week and never goes above 2 lb, with no dates.
4. You see a weight trend as well as today’s number, and you can hide the number.
5. Each food entry names where its calories come from.
6. There are no streaks, rewards or countdown timers.
7. You see the price, the trial and the way to cancel before the quiz.
8. You can export your diary on any plan.

Items 2 and 6 are the two I would never give up, and the trend chart is the first thing I’d drop.

How do I test an app in a 10-minute trial?

Open the app before you pay and give it ten minutes. The table turns the eight points above into eight quick tests, in the order I would run them.

Point	Do this	It fails if
1. Quick logging	Log your usual breakfast, then log it again from history	the second log takes more than a couple of screens
2. Safe floor	Type a goal far below the floor on purpose	the app saves it, or hides the warning behind a tap
3. Pace and dates	Choose the fastest pace on offer and look for a finish date	it shows a date, or lets you pass 1 kg (2 lb) a week
4. Trend	Add two or three weights from different days and open the chart	you see only today’s number, or no way to hide it
5. Source of calories	Open an entry you know well, such as cooked rice	the entry is a bare number with no record or state
6. No pressure	Look through settings and the paywall for streaks, badges and timers	any of them is there
7. Price and cancel	Find the price, the trial length and the cancel route	the price comes only after the quiz, or cancelling needs an email
8. Export	Find the export button on the free plan	it is missing, or it needs a paid plan

Write down the tap count for test 1. Run the same list on a second app. Two scores beat two impressions.

What should the first two weeks look like?

1. Day 1. Set the goal from your maintenance number, choose the slowest pace and log the day as you eat.
2. Days 2 to 7. Log at the table. Weigh on the same mornings each week, or skip the scale and track food only.
3. Day 8. Look at the trend instead of the day. One high morning is noise.
4. Day 14. Divide the change in your trend by two to get kilograms a week. Between 0.5 and 1 kg fits the NHS range. Faster than that, raise the goal.
5. Decide. Keep the app if your repeat meals log in under a minute and you did not dread opening it. Otherwise cancel before the trial ends.

What if the scale stalls or the goal feels too low?

Two flat weeks do not yet mean the plan has failed. In the 2011 model above, a steady goal draws a line that bends toward flat, because weight responds slowly to a change in intake.

Check three things in this order. First the log: weigh the oil and spreads you usually guess, for one week. Then the window: compare weigh-ins from the same weekday. Last, the goal: change it in small steps and keep it above the floor.

A goal at the floor that leaves you hungry or tired all day calls for a higher goal and a slower pace. Treat 1,200 and 1,500 kcal as the lowest point of those ranges and move up from there. Dizziness or weakness is a reason to call your doctor.

Run the ten-minute test on two apps and write down the taps for test 1 and every fail. Keep the one that costs you less effort and delete the other before its trial renews. Then put a reminder in your calendar for day 14, when the first trend check is due.

If counting calories has started to feel hard to stop, or eating feels out of control, talk to someone: ANAD in the US (1-888-375-7767), Beat in England (0808 801 0677), NEDIC in Canada (1-866-633-4220) or the Butterfly Foundation in Australia (1800 33 4673). If you’re in danger right now, call your local emergency number. Other UK numbers and crisis lines are on our crisis support page.