Fitness Watches and Nutrition Apps: Behavioral Benefits and Emerging Concerns : ACSM's Health & Fitness Journal

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Fitness Watches and Nutrition Apps: Behavioral Benefits and Emerging Concerns

Scheid, Jennifer L. Ph.D., CSCS; Lupien, Shannon P. Ph.D.

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ACSM's Health & Fitness Journal 25(2):p 21-25, 3/4 2021. | DOI: 10.1249/FIT.0000000000000644
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In a worldwide survey of fitness trends published by ACSM’s Health & Fitness Journal®, wearable technology was one of the top three fitness trends from 2016 through 2021 and became the number one reported trend in 2016, 2017, 2019, and 2020 (1,2). Wearable technology typically includes devices worn on the wrist, chest, arm, hip, or any other part of the body that can measure physical activity through movement, heart rate, or Global Positioning System (GPS). Fitness watches, devices worn on the wrist and made by companies like Apple®, Fitbit®, Garmin®, Misfit®, and Polar®, have become particularly popular and have a number of fitness-related capabilities. At a basic level, most fitness watches function like pedometers or accelerometers. Pedometers measure number of steps taken, and accelerometers measure movement in multiple directions. Upgraded fitness watches also employ heart rate and GPS technology. This information can be combined with the pedometer and accelerometer data to give more detailed information about daily physical activity and sedentary behavior, such as reaching moderate or vigorous activity levels based on a percentage of maximal heart rate during exercise. These fitness watches also can be integrated with other health-promoting technology, such as nutrition apps, to provide a more complete picture of one’s health-related behaviors.


Nutrition apps like MyFitnessPal® ( and Lose It!® ( track food and beverage consumption using a searchable database. This provides information regarding consumed calories, macronutrients, and micronutrients for each snack or meal, or for daily and weekly totals. Given that many fitness watches integrate information from these nutrition apps, a client can gain a more thorough understanding of both energy intake and energy expenditure. Some fitness professionals may recommend combining the use of fitness watches and nutrition apps as a way to help coach clients through weight loss. In a 2015 study, 72% of fitness professionals reported that their clients asked them for insight or feedback on wearable technology (3). This article will explore these technologies, discuss potential health improvement benefits, and explore potential limitations and associated cautions that should be considered.


Self-monitoring is a powerful behavior change tool that has been shown to be a successful strategy for achieving certain health goals such as weight loss. For example, self-monitoring one’s food intake can have a beneficial effect on healthier eating habits and has been reported to improve success during weight loss interventions (4,5). During a 6-month weight loss intervention with 1685 overweight and obese adults, a significant predictor of weight loss was the number of food records kept (5), indicating that the more food records the adults kept, the more weight they lost. If clients are monitoring their food intake by writing down all the food they eat on a piece of paper (or any other type of nutrition log), the very act of writing down the food can make the clients more aware of everything they are eating. Self-monitoring also may make a client more aware of whether or not they overeat in specific situations, i.e., if they have any triggers that lead them to overeat (6). Theoretically, clients will make a purposeful decision to eat certain items because they are thinking more about what they are eating and may not want to write down the extra snack they would have normally eaten. Self-monitoring strategies also are relevant for physical activity (4). For example, people with mostly sedentary lifestyles may not realize how little they are moving in a given day, but keeping a physical activity log allows them to recognize how little they may actually be moving in comparison with specific recommendations (6).


One reason for clients’ success when using fitness watches and nutrition apps is that they are using self-monitoring techniques that provide awareness of food and calorie intake, and movement and exercise, as well as encouraging clients to monitor their outcome goals, such as body weight (4,6). In addition to traditional benefits of self-monitoring, fitness watches and apps can provide added convenience (4). Instead of having to carry around a nutrition or fitness log or remember to enter everything accurately at the end of the day, clients can use fitness watches and nutrition apps to more easily track their movement and food intake in real time. Furthermore, clients can set caloric and activity goals through their fitness watches and nutrition apps that theoretically may help them meet their health and fitness goals by providing reminders to self-monitor their behavior in order to stick to their goals (4,6).

In addition, nutrition apps not only provide traditional self-monitoring by allowing clients to log the food that they have eaten but also give clients feedback about the nutritional value of the food they are recording. These apps estimate the total calories and associated macro- and micronutrients for each item of food that the user provides. Clients can immediately see their total calories for the day, which helps provide awareness about the value of different food and drink items beyond just an awareness of the overall amount of food they are consuming. For example, clients may have written down their venti green tea frappuccino and a had vague understanding that it was not the healthiest choice, but they might not have realized that it contained close to a third of their entire daily recommended caloric intake. A number of studies show success for the use of nutrition apps and improved health outcomes. For example, a systematic literature review revealed that each of the four research studies that met inclusion criteria provided evidence that nutrition apps were able to provide an advantage for weight loss compared with traditional self-monitoring, primarily through increased adherence to self-monitoring one’s diet (7).


Fitness watches also go beyond the simple self-monitoring techniques of logging one’s exercise by allowing clients to see their real-time movement and physical activity throughout the day. Fitness watches can make the client more aware of their overall daily activity and can help them increase their daily movement to align with their predetermined physical activity goals by setting reminders for when they have not moved in a while or when they are close to their goal for the day. This has been shown to be successful for improving health and weight loss. Painter and colleagues (8) conducted a retrospective analysis following a 6-month weight loss study (the study included the use of Fitbit activity monitors and an online/mobile nutrition tracking system) in adults who lost at least 5% of their body weight. Significant predictors of weight loss at 6 months included the number of weigh-ins per week, the number of steps per day, at least 60 minutes of high-intensity exercise, and food logging at least 5 days per week. Thus, overweight and obese individuals in a 6-month weight loss program experienced improved success by using fitness watches to self-monitor daily steps and high-intensity exercise (8). Furthermore, the study suggests that integrating fitness watches with nutrition tracking systems has benefits for health and weight loss.

Specifically, integrating fitness watches with nutrition apps may help an individual to more fully monitor their health behavior. For example, individuals can see their net calories after accounting for the food they have ingested as well as the calories that their bodies have burned from exercise and movement throughout the day. They can then compare their overall calorie deficits to those recommended for healthy weight loss and can check their actual body weight as they progress.

In summary, fitness watches and nutrition apps help clients self-monitor their nutrition, physical activity, and body weight. From a behavioral standpoint, it does not necessarily matter how fancy the technology is that is used to self-monitor. The client sets daily or weekly goals and then records their progress to see how they measure up to their goals. However, fitness watches with integrated health and nutrition apps can streamline this process by automatically recording physical activity and integrating this information into nutrition apps, which may make it easier for a client to self-monitor and reap the associated benefits of the intended behavior change, i.e., increased physical activity or improved nutrition. Self-monitoring is a powerful behavior change tool, and integrated fitness watches can provide a convenient way to self-monitor health behavior (4).


Although fitness watches and nutrition apps can have important health benefits, there are some limitations that may impact their long-term effectiveness in helping clients to reach their health goals. Although wearable technology is currently very trendy (1,2) and can make self-monitoring more convenient, evidence suggests that clients may stop using wearable technology over time, thus preventing the long-term benefits that the device may provide. For example, a Gartner Personal Technologies survey of close to 10,000 individuals revealed that nearly 30% of fitness watch owners stopped using them not long after purchase (9).

In addition, there are reports that there may be little to no benefit of using fitness trackers compared with other weight loss methods. For example, one study examined participants who were randomly assigned to a weight loss program, a weight loss program plus wrist-worn fitness tracker, or a control group. Results indicated that at 3 months, those who were in the weight loss only program differed from the control condition, resulting in greater weight loss, but the weight loss plus activity tracker condition did not differ from the control (10). In addition, a study comparing a traditional self-monitoring weight loss approach to the same approach accompanied by an arm-worn fitness tracker indicated that over time, the traditional approach was more successful. Although the two groups did not differ after 6 months, at 12, 18, and 24 months, the traditional self-monitoring approach led to greater weight loss than the approach paired with the fitness tracker (11). Thus, it is important to understand more about how fitness watches may lead to benefits in some cases but not in others. Given that fitness watches have been shown to be a convenient way to integrate multiple aspects of one’s health to provide a more complete picture, they may differ from other types of activity monitors that have not been shown to be successful.


Health-tracking behavior can sometimes go too far and become unhealthy if clients develop an extreme or obsessive focus on counting calories and continually increasing exercise goals. For example, using fitness and nutrition apps may trigger or exacerbate clients with preexisting eating or obsessive psychopathology; an extreme focus on body weight, food, and caloric intake are behavioral signs of anorexia nervosa (12). Although only an association, emerging research suggests that using fitness trackers and nutrition apps may increase risk for a client who is predisposed toward developing disorders like anorexia nervosa, body dysmorphic disorder, and obsessive–compulsive disorders because of their focus on tracking food and exercise (13,14). These technologies may not necessarily provide any additional risk factors when compared with traditional self-monitoring techniques. However, given the popularity and ease of use of wearable technologies, individuals with the aforementioned predispositions might be more drawn to them, and this could potentially fuel or exacerbate their disordered behavior.

Recently, specific associations have been made between calorie tracking and symptoms associated with eating disorders, such as eating concern and dietary restraint (13,14). Simpson and Mazzeo (13) surveyed 493 college students and demonstrated an association between using calorie trackers and higher levels of eating concern and dietary restraint measured by the Eating Disorder Examination Questionnaire, even when researchers controlled for body mass index (BMI). This indicates that it might not matter if someone has a high or low BMI and is potentially already eating and exercising in healthy amounts; if they are using a nutrition app to track their calories, they may be more likely to be concerned about eating or have a higher dietary restraint, both of which have been associated with symptoms of eating disorders (13). Similarly, Plateau and colleagues (14) surveyed 352 college students and also demonstrated an association between using food intake/physical activity monitors and eating concern, weight concern, and dietary restraint, measured by the Eating Disorder Examination Questionnaire. Users of food intake/physical activity monitors also had increased exercise compulsions measured by a Compulsive Exercise Test and increased purging behaviors via exercise, also measured by the Eating Disorder Examination Questionnaire, compared with nonusers of food/physical activity monitors. Furthermore, in a study examining individuals who had successfully lost weight following slimming competition interventions, participants exhibited higher levels of dietary restraint and weight, shape, and eating overconcern as well as higher levels of emotional eating than a nondisordered population (15). Although elevated dietary restraint is not necessarily a concern, and is typically a crucial component to producing maintained weight loss, extreme dietary restraint is associated with eating disorders.

In addition, self-monitoring may be associated with other negative physiological consequences. For example, self-monitoring of body weight was associated with lower levels of self-esteem and/or higher levels of stress (16). If self-monitoring reveals that clients are not meeting their body weight, physical activity, or caloric intake goals, this may lead to self-esteem deficits and higher stress levels. Furthermore, an intervention strategy often employed by fitness and nutrition apps to increase motivation involves the use of competition and social comparison combined with self-monitoring. For example, Fitbit® offers challenges within the app, which encourage competition with friends and family to gain the most steps within a given day or workweek. The Apple Watch® allows individuals to share their activity rings (progress toward their movement, exercise, and stand goals for the day) and set up challenges and competitions with each other. Moreover, MyFitnessPal® allows users to “friend” others and create groups in which individuals can compete in various types of challenges. Although these challenges and competitions can be motivating and provide incentives (17,18), they also may create unhealthy or unrealistic social comparisons, unattainable goals, and decreased self-efficacy.


Although this research is only beginning to emerge, exercise professionals should understand that fitness watches and related apps may potentially contribute to negative outcomes, such as the following:

  • ○ eating disorder’s
  • ○ lowered self-esteem
  • ○ negative body perception

Before giving advice on wearable technology, exercise professionals might consider the following:

  1. Obtaining medical and health histories (including psychological health) of each client before helping those clients to develop healthy eating and fitness behaviors.
  2. Creating realistic goals and discouraging unrealistic social comparisons.
  3. Keeping a look out for behaviors of psychological disorders that may be observed in a fitness setting:
    • ○ Anorexia nervosa: preoccupation with weight, food, calories, fat grams, and dieting.
    • ○ Bulimia nervosa: preoccupation with weight, food, calories, fat grams, and dieting and exercising as a form of purging.
    • ○ Obsessive–compulsive disorder: obsessively weighing, measuring, and recording all food and/or obtaining specified (often excessive) exercise goals. Often coupled with an eating disorder
    • ○ Body dysmorphic disorder: excessive exercise.
  4. Referring to physicians, psychologists, or nutritionists if they are concerned about disordered eating behavior in their clients.


Self-monitoring is a powerful behavior change tool, and integrated fitness watches can provide a convenient way to self-monitor health behavior. Health and fitness technology, including wearable technology and nutrition apps, can help clients set goals and self-monitor nutrition, physical activity, and body weight leading to positive outcomes. Emerging research suggests that using fitness watches and nutrition apps may not always be beneficial and in some cases can lead to a number of negative outcomes. Knowing that fitness watches and related apps may potentially contribute to negative outcomes, such as eating disorders, lowered self-esteem, and negative body perception, highlights the importance for exercise professionals to obtain thorough medical and health histories (including psychological health) of each client before helping those clients to develop healthy eating and fitness behaviors.


Self-monitoring is a powerful behavioral change tool, and fitness watches and nutrition apps are popular, modern technologies that can employ self-monitoring techniques to promote healthy behaviors. The purpose of this article was to explain how these technologies can promote self-monitoring, and also to review some potential concerns that these technologies may create. For example, there may be an association between excessive self-monitoring of physical activity and nutrition and certain disordered behaviors, such as anorexia and other obsessive health behaviors. Thus, it is important for fitness professionals to understand how each client may respond differently to these technologies. Care and concern are important when recommending wearable technology, as is having resources available if the fitness professional suspects disordered behavior and excessive use of these technologies in their clients.


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Wearable Technology; Self-monitoring; Fitness Watches; Nutrition Apps; Disordered Eating

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