What is the best app for weight loss? What to look for

If you are looking for an app to lose weight, the useful question is not which one has the most downloads but what makes an app genuinely help. Here is what the studies say, a checklist of what to look for, how seven well-known apps set the calorie target, and what vitaloop, a nutrition app made in Barcelona, does. We are the team that makes it; everything we say about other apps comes from their own store listings and sites, linked, read on 13 October 2026.

What the evidence says

1. Logging works, if you keep it up

Logging what you eat and weighing yourself is the centre of behavioural weight-loss programmes. A systematic review of 22 studies consistently found a significant association between self-monitoring and weight loss, although the level of evidence was limited by the studies' design (Burke, Wang and Sevick, Journal of the American Dietetic Association, 2011). With digital tools, a review of 39 randomised trials found that more self-monitoring was linked to more weight loss in 74% of the cases analysed (Patel, Wakayama and Bennett, Obesity, 2021). Consistency is what counts, which is why logging has to be quick.

2. A fixed calorie target drifts

Many apps set your target with a formula from age, sex, height, weight and activity. Even the equation that does best in comparisons, Mifflin-St Jeor, has “noteworthy errors” when applied to an individual (Frankenfield et al., Journal of the American Dietetic Association, 2005). And your expenditure changes: as you lose weight, you burn less. In Hall and colleagues' model, every permanent change of 100 kJ a day (about 24 kcal) eventually moves body weight by about 1 kg, and it takes about a year to get halfway there. The familiar 3,500 kcal per pound rule ignores these adaptations (Hall et al., The Lancet, 2011). In practice, a target set on day one is no longer the same deficit a few weeks later. What makes sense is a target that follows how your weight actually moves.

3. Enough protein while you eat less

In a meta-analysis of 24 trials with 1,063 people on diets of about 12 weeks, at equal calories the higher-protein diet produced 0.79 kg more weight loss and 0.87 kg more fat loss, and preserved 0.43 kg more fat-free mass (Wycherley et al., American Journal of Clinical Nutrition, 2012). An expert review places the benefit in diets of 1.2 to 1.6 g of protein per kg of body weight a day, with about 25-30 g per meal (Leidy et al., American Journal of Clinical Nutrition, 2015). If your protein target is a percentage of calories, it drops exactly when you eat less.

4. Eating less also means fewer vitamins and minerals

The suggested menus of four popular diet plans, averaging about 1,750 kcal, met the reference for about 12 of the 27 micronutrients analysed. Even leaving out six that were short in all of them, about 3,475 kcal a day would be needed to cover the other 21 (Calton, Journal of the International Society of Sports Nutrition, 2010). In three commercial weight-loss plans, even scaled to 2,000 kcal, vitamin D was still short in all three and calcium in two (Engel et al., Nutrients, 2018). When you eat less, each food has to bring more, and to know whether it does you need to see iron, calcium or magnesium, not just calories.

What to look for in a weight-loss app

• Logging that takes little effort: a search with local food, a barcode scanner, meals you repeat. If it is a chore, you will stop.
• A calorie target that adjusts to how your weight changes, not just a day-one formula.
• A concrete target weight and a moderate pace to reach it, with no extreme calorie targets.
• A protein target that does not sink when calories go down.
• Vitamins and minerals in view, packaged products included.
• Help reading the scale: day-to-day weight goes up and down with water; the trend is what matters.
• Your language and your food, and knowing what is free and what is paid before you start.

How well-known apps approach it

These are the apps that come up most when people ask for an app to lose weight. We do not rate which works better: we record what each one says about itself.

• MyFitnessPal: its listing says your workouts affect your daily calorie goal. According to its Premium page, nutrition and weight tracking is free, while the barcode scanner and custom macro goals are Premium.
• Noom: its listing describes a subscription that renews after a 7-day trial and does not say how it sets calories.
• Fitia: according to its listing, Fitia Coach adjusts your plan to your progress, and its database includes Latin American and Spanish foods. Its blog says it tracks 12 vitamins and 9 minerals.
• Yazio: its listing mentions customisable calorie goals and, in PRO, a personalised calorie plan.
• MacroFactor: its listing says its expenditure calculation detects changes in your metabolism and adjusts calorie and macro targets weekly (explained on its site). It is in English and Japanese and has no free plan.
• Lose It!: according to its listing, it calculates a daily calorie budget from your profile and goal weight; Lose It! Basic is free.

What vitaloop does

• A calorie target that gets more precise over time. A formula only knows your age, height and activity, and we have seen why it drifts. If you also log your weight, vitaloop's nutrition intelligence system estimates how much energy you burn each day from how your weight actually moves together with what you eat, and your calorie target follows that real expenditure. The more you log, the more precise it gets. And as you approach your target weight, the deficit eases off.
• A numeric target weight. You say what weight you want to reach and the app sets a moderate pace, never proposing a calorie target below a prudent minimum.
• A protein target tied to your weight, which does not drop when calories do.
• 13 vitamins and 13 minerals while you eat less, against European (EFSA) reference values for your age and sex. Scanned products too: the nutrition intelligence system estimates their vitamins and minerals and marks them as estimates. More in what vitamins and minerals are in a scanned product and which app calculates the vitamins and minerals in what you eat.
• Your weight trend, not one day's number. vitaloop shows where your weight is heading and when you would reach your target at this pace.
• Patterns in your own data. For example, whether the scale reads higher the morning after a saltier day: that is water, not fat. How vitaloop finds these patterns: patterns in what you eat.

Logging what you eat, the calorie target that adjusts to your weight, the target weight, the protein target and vitamin and mineral tracking can all be used for free.

Losing weight sensibly

• A realistic pace.The UK's NHS advises losing weight steadily, 0.5 to 1 kg a week (NHS).
• No extreme deficits. Eating very little makes it harder to cover protein, vitamins and minerals, and harder to keep going.
• Talk to a professional first if you have or have had an eating disorder, are pregnant or breastfeeding, or have a medical condition or take medication. vitaloop is for adults (18+), is not a medical device and does not give medical advice.

Is vitaloop for you?

If you want a calorie target that adjusts to how your real weight evolves, a protein target to keep muscle, and to see your vitamins and minerals while you eat less, packaged food included, vitaloop is for you.

vitaloop works natively in English, Spanish and Catalan and is a free download on the App Store and Google Play, for iPhone, iPad and Android phones and tablets. To compare it with other nutrition apps, see the best nutrition apps in Spain.