Frequently Asked Questions about Using Apps for Weight Loss

By Jennifer Rosenbaum, MD

Apps for weight loss are incredibly common. So as a physician, I receive a lot of questions from my patients about using them. If an app is the right tool for you, I’ve put together a list of the most common questions that I receive to try to help you make the most of your app experience.

Should I use an app for weight loss?

There are a lot of apps designed to help with weight loss. Most of them have not been studied to prove that they achieve the goals they claim. However, we do know that keeping a food journal and counting calories are associated with successful weight loss, and apps can be great for those activities. Your cell phone has a few advantages over pen and paper. First, most people have their phone with them all the time, so it’s more convenient than a paper log. Second, it can be easier to look up things like calorie counts and add up your total calories for the day. If you’re a person who carries a smartphone frequently and wants to lose weight, it might be a good option for you to try.

Which app do you recommend?

There is no one best app. Apps have diverse features such as tracking different macronutrients (carbohydrates, protein and fat) in addition to calories, tracking exercise, accessing community support forums, and so forth. Finding one that meets your needs and is easy for you to use is key. An app that you will use consistently is what is most important. If you try an app and find the interface confusing or difficult to use, then try a different one. If there is one that your friends use and enjoy, that might be a good one to try first. Oftentimes you can share food logs or achievements with friends, and that accountability and community support might be helpful.

My app gives me a calorie goal. Is it the right goal? What calorie goal should I use?

This is a tricky, complicated question. Research says 3,500 calories is equal to a pound. If you want to lose a pound a week, then you would want to eat 3,500 calories less than you burn each week, or 500 calories less than you burn each day. The question is, how many calories does your body burn each day? This depends on how tall you are, how much muscle you have, how active you are and other factors. If you have lost weight previously, you probably burn fewer calories each day than someone your exact same height and weight who has never lost weight before. Most apps have a built-in calculator to give you an estimate of what your daily calorie goal should be. Generally, these are pretty good estimates, but remember that it’s just an estimate.

Is the app giving me the right macronutrient goals? Should I eat low-carb or low-fat foods?

There are a lot of diets available that focus on low-fat or lowcarbohydrate foods. Many apps will set different macronutrient goals for you that may or may not fit with what is right for you. What’s most important is to eat a diet that is medically healthy. For example, people with kidney disease should probably avoid high-protein diets because the diminished kidney function can affect the ability to eliminate all of the waste products of protein metabolism. Low-carbohydrate diets can be great for people with diabetes, but should be started with caution since reducing carbohydrates can greatly impact your blood sugar and how much medicine you need for your diabetes. As long as you’ve talked to your doctor about changes to your diet and it is medically safe for you, there does not seem to be one best diet plan.

Many apps will allow you to set different goals based on whatever you would like to do. In general, the studies that have examined different kinds of diets in medicine seem to show that low-fat versus low-carb diets can both result in weight loss. A diet that you can stick with is the diet most likely to work.

If you get cravings for items such as popcorn and cookies when you are on a low-carb diet, try to find a diet where you can count those towards your calorie goal. If you don’t feel full on a low-fat diet, a low-carb diet may make you feel more satiated and result in fewer cravings. Or, perhaps try more vegetables, which can give you more food volume without an abundance of calories. Give whatever diet plan you choose a try. Don’t worry too much if you have one bad day or “fall off the wagon.” The trick is to get back on it again. If you find you’re unable to stick with the diet, try to figure out what about the diet did not work for you. Were you too hungry? Were there specific foods you were craving? Adjust your plan to try and avoid those pitfalls on your next attempt and try again.

My app warns me if I don’t eat enough. Is it possible to eat too few calories?

There’s a lot of debate in the app forums about “starvation mode” and whether eating too few calories actually inhibits weight loss. It is definitely possible to get sick from not eating enough, and it’s debated whether not eating enough can slow weight loss. What we do know is that your body needs certain vitamins and nutrients each day, and the less you are eating, the harder it can be to get those essential nutrients. In general, eating less than 1,000 calories a day puts you at higher risk for not getting the nutrition that your body needs. When you are on a calorie-restricted diet, it becomes more important to eat nutrient-rich foods like vegetables to make sure that you are getting enough nutrients in your limited consumption.

But my app says I should eat more. Should I eat more if I am under my calorie goal at the end of the day?

The short answer is probably not, assuming that you are eating enough to meet your basic needs. Many apps tell you that if you are under your calorie goal for the day, then you should eat more. This often is related to the question above about eating too few calories and concerns for “starvation mode.” Remember that the calorie goal you have is an estimate. We don’t really know how many calories you burn on an average day, so we want to see it as an estimate and not a rule. Similarly, calorie counting is an estimate. Did you put ketchup on that burger? Just how much ranch dressing was on your salad? For some people, it’s probably a very good estimate – if you are cooking all your own food, weighing it on a food scale and eating every last morsel, you’re probably pretty close to how many calories you ate that day. But most people are not quite so exact. Some people overestimate portion sizes and some underestimate them. Some apples are bigger than other apples. Sometimes we forget to account for the oil we used for cooking, and sometimes half of your yogurt sticks to the side of the bowl. Some entries in the food database list an egg as 60 calories while others say 85. Which is right? With all these different calorie count factors, if you’re not hungry at the end of the day, don’t eat more just to meet a goal, since the numbers aren’t that accurate.

My app keeps track of my exercise and then adjusts my calorie goal for me. Should I eat my exercise calories?

My father called me very upset last week. He was on vacation and the treadmill at the hotel told him he burned half as many calories as his treadmill at home says he burns doing the exact same workout. He desperately wanted me to tell him which was right. As tempting as it was to make him feel better by saying the machine with the higher calorie estimate was right, the real answer was that I didn’t know. Most likely, both machines were wrong. It’s tricky to calculate how many calories are burned during exercise. We can make an estimate based on your height and weight, but our estimates are not very good, as the machines with widely varied calories-burned results showed my dad. If you did the same run every day for a month, you would probably have a much easier time doing it by the end of the month. That easier time is a reflection of your body becoming stronger and more efficient at the exercise. Unfortunately, it also means you’re burning fewer calories doing it.

Consider two people, one who is very active all the time and the other who never leaves their couch. Their daily calorie goals have been set based on their activity level, so an active person is allotted more calories to eat per hour than the inactive person. If the active person and inactive person go for a run together, they might burn the same number of calories, but it’s more calories for the inactive person relative to how he would have otherwise spent that hour. Suddenly we are making complicated math even more complicated. Further, newer studies suggest that if you exercise for many hours, you don’t burn as many calories later in the workout as you did at the beginning because your body finds a more efficient mode.

So how do the apps calculate how many extra calories you get for exercising? Well, probably as accurately as my dad’s treadmills. But exercise does burn calories and can make you hungry. If you exercise, it’s reasonable to eat more that day. Just be cautious when eating those exercise calories as, sadly, you probably didn’t burn quite as many calories as you would have hoped. Eating an extra 100 to 200 calories on exercise days is probably reasonable.

Do my steps count as exercise?

Pedometers are everywhere these days. Most phones are acting as a pedometer, and many apps take advantage of that to show you how active you’ve been. Though some with a pedometer use it to motivate themselves to increase physical activity, more often people just wear it and monitor what they would already be doing. If the pedometer is counting what you do normally, and that level of activity was already taken into account with your original calorie goal, then you would be double-counting the calories if you put them in the exercise category.

Walking is wonderful exercise. It’s been shown to be one of the exercises people are most likely to continue to do on a regular basis and least likely to lead to injury. But not every step is the same. Try taking 40 nice slow steps around your kitchen. How do you feel? Now try walking up three flights of stairs. Although those are likely very similar step counts, you likely feel a little more tired after walking up those stairs. Similarly, recognize that hitting your step goal by going for a run burns more calories than hitting your step goal just walking around during the day. Don’t let your daily steps turn into an excuse not to exercise. Try to use your step goal to push yourself to do more, and don’t avoid beneficial activities such as riding a bike, going for a swim or lifting weights just because they won’t raise your step count.

What tools for weight loss are missing from apps?

Obviously, there is no single answer for how to lose weight, but there are a lot of things that we know do or do not work. Though apps have a lot of strengths, it takes more than use of an app to help with weight loss. This includes accountability to other people and social support. Whatever approach you take, we know it will be enhanced if you engage other people. For example, Weight Watchers has had great success with its group classes. Peer pressure seems to be a benefit in this instance. And from television shows to friendly office competitions, we know people tend to lose weight when competing. A small wager with a friend or relative can provide a huge incentive. For me, my bet is that you can indeed lose weight.

In conclusion:

  • Weight loss apps can help better log your efforts than pen/paper

  • Calorie estimates are just that - estimates

  • Physical activity estimates are just that - estimates

  • Personal efforts at changing lifestyle can be more successful when done with a group