Diet apps are software applications for tracking nutritional intake and managing diets for healthy eating, weight loss, weight maintenance, weight gain, and fitness. Diet apps are also used to track food sensitivities, allergies, and medical conditions, such as diabetes, high blood pressure, and heart disease. Most diet apps are tools for mobile devices, such as smart-phones and tablets.
Millions of people worldwide follow weight-loss diets or track their nutritional intake or avoid certain types of food for medical reasons. With the proliferation of smartphones and other mobile devices, apps have made following prescribed diets significantly easier, more convenient, and less expensive. Some diet apps function as companion tools for diet books or online or in-person weight-management programs such as Weight Watchers.
Approximately two-thirds of U.S. adults are overweight or obese, with more than one-third considered obese, compared with only 15% in 1980. One-third of American children and adolescents are either overweight or obese, including almost 40% of African American and Hispanic children. About 17% of all U.S. children and teens are considered obese. This is three times the prevalence in 1980. Diet apps can be very powerful tools for helping people track calories and lose weight while maintaining balanced nutrition. Not only can diet apps make it easy to monitor calories and intake of carbohydrates, proteins, fats, and other nutrients, many of them perform calculations and provide information that was previously unavailable to the typical consumer. They can even suggest healthy meals and recipes.
Diet apps are also useful for nutrition and weight-loss research, because traditional methods for studying food intake—surveys or food diaries—are notoriously inaccurate. For example, researchers developed a smartphone app that used phone cameras to reveal that many adults eat as many as 10 or more times over a period of 15 hours or more each day, which may negatively affect metabolic health. This study showed that by limiting eating to a 10–12-hour window, overweight participants using the app reduced their caloric intake by an average of 20%, and most lost several pounds.
Nearly 30,000 weight-management apps were identified for download from app stores in industrialized countries in 2016. There are even apps for selecting a diet app. Although some diet apps are dual- or multipurpose, many are designed for specific purposes and goals, such as maintaining a low-carbohydrate diet, managing diabetes, or losing weight at a specific rate, such as 0.5–2 lbs. (0.2–0.9 kg) per week. Many diet apps are free or very low cost, although some have fairly high subscription fees for full functionality. Some diet apps have different language selections or are designed specifically for travelers. Researchers categorized the primary focus of identified diet apps as:
Procedures for using diet apps vary as much as the apps themselves, starting with their registration and navigation functions. Some are designed to be used in conjunction with specific weight-loss programs. Others are better used under the guidance of a registered dietitian, especially if disease management requires a carefully controlled diet. Some diet apps readily integrate with social media, such as Facebook and Twitter.
Most diet apps involve keeping food logs by typing in, voice logging, or photographing foods consumed over the course of the day, or by scanning bar codes. Calories, foods, nutrients, weight, and exercise may be tracked on a daily, weekly, or monthly basis, depending on the app, and graphs may show weight and progress over time. Tracking can include:
Some diet apps calculate an individual's body mass index (BMI), basal (resting) metabolic rate, and the thermal effects of exercise, based on gender, age, height, weight, and activity levels. Such apps may then calculate target caloric intakes or design customized daily meal plans for a given weight-loss rate or specific target date. Some apps include recipes, shopping lists, tips, reminders, and rewards for meeting goals. They may assist users in choosing options, such as healthier pizza or a different cocktail. Some apps send daily informational and inspirational articles and success stories. Some include databases of calories burned with physical activities or specific fitness exercises. Others include online communities and forums for support and enable users to add friends.
Many diet apps, both in the United States and elsewhere, use national nutrient databases from the U.S. Department of Agriculture (USDA). These science-based nutritional databases can be downloaded free-of-charge by both commercial and nonprofit application developers. The USDA's National Nutrient Database for Standard Reference is considered the authoritative source on food composition and serves as the foundation for most food and nutrition databases used in the United States. It includes nutrient profiles of single- and multiple-ingredient foods, including raw, cooked, processed, and prepared foods, from raw eggs to frozen lasagna.
Apps for managing diabetes, celiac disease, food allergies, or other conditions generally include functions in addition to weight loss. Managing diabetes requires careful, consistent logging. In addition to total calories, diabetes-management apps track intake of carbohydrates, fat, protein, fiber, specific foods, and water, as well as activities and exercise over the course of the day. They usually track blood sugar levels, set target ranges, rapidly identify unsafe readings, show trends over time, and even schedule meals. They may track insulin injections and dosages, as well as other medications. The apps send hypoglycemia and hyperglycemia alerts and may note abnormalities in medication, exercise, fat or alcohol intake, or meal times. They may even track blood pressure and pulse. The apps may include diabetes-management education, advice on food choices and recipes, and connections to online diabetes-management communities. Of particular benefit, diabetes apps can export logs directly to healthcare providers for review and analysis.
Diet apps for people with food allergies or sensitivities can be customized with specific restrictions. Some specialized apps, such as gluten-free diet apps, can be adapted for other sensitivities and for vegan diets. Such apps often include special diets, menus, and shopping lists. They may include lists of allergens and specific allowable products and certifications. By scanning bar codes, they may be able to determine the safety of foods based on specific allergen restrictions.
Some specialized diet apps include medication guides, information on food additives, links to tips and other resources, and sites for sharing experiences and recommendations. They may rate restaurants based on their ability to accommodate dietary restrictions and even provide directions to restaurants via GPS.
Weight-loss apps on various US 2017/2018 “best” lists included:
Recommended specialty apps include:
There is little evidence that diet apps help people lose weight. Very few apps have been tested by people using them on their own. Those that have been evaluated have yielded either poor results or better results only if used in conjunction with support from a dietician or health coach. This is not surprising, because human interaction has been shown to be an important component of patient management and behavior modification required for weight loss. Although calorie counting has been shown to be important, most weight-loss apps have fewer than 10% of other elements that appear to contribute to successful weight loss. As of 2018, improved diet apps had been introduced, and some had been tested in clinical trials.
Studies of popular diet apps have reported that most are of low quality. A 2016 study of nearly 29,000 diet apps found that only 17 had been developed with any identifiable input from healthcare professionals. Diet apps designed for similar purposes vary greatly in their capabilities, information, databases, graphics quality, ease and convenience of use, and help and support functions. Some apps are much faster than others, and some are more reliable. Many require internet access. Although many diet apps track calories and at least some nutrients—such as carbohydrates, protein, and total fats—many do not track other important nutrients, such as saturated fats, fiber, or sodium.
Researchers who have studied weight-loss programs suggest that apps should provide:
Studies have shown that people are unlikely to use apps that require them to log in data. Warning signs of poor-quality diet apps include:
Diet apps can be awkward or confusing to use. The databases may be limited or provide information that is confusing, overly technical, misleading, or out-of-date. Some apps list amounts in only one system, such as ounces or grams. Although some diet apps may offer Wi-Fi backup and restore functions, others lack systems for automatically backing up records. Certain apps have problems scanning bar codes. Although many diet apps are inexpensive or free for download, their capabilities may be quite limited, and they may have advertisements. Some are free for a limited trial, but user-entered information may be lost unless the app is subsequently purchased.
Diet apps can have privacy and security issues, although some are password protected. In particular, diet apps that access Twitter or online forums or communities can raise serious privacy issues or put the user at risk for false or misleading information.
Various diet apps are available for kids. PapayaHead was the runner-up in the “Apps for Healthy Kids” contest sponsored by former First Lady Michelle Obama and the USDA. PapayaHead and diet apps such as Kurbo Health Coaching are designed for use by the entire family. The Sugar Smart app was launched in 2016 in the United Kingdom to help parents determine the amounts of sugar in common foods and drinks.
See also Body mass index ; Calories ; Mayo Clinic plan (official) ; Weight Watchers .
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Academy of Nutrition and Dietetics, 120 S. Riverside Plaza, Ste. 2190, Chicago, IL, 60606-6995, (312) 899-0040, (800) 877-1600, email@example.com, http://www.eatright.org .
American Society for Nutrition, 9211 Corporate Blvd., Ste. 300, Rockville, MD, 20850, (240) 428-3650, Fax: (240) 404-6797, http://www.nutrition.org .
Center for Food Safety and Applied Nutrition, Food and Drug Administration, 5001 Campus Dr., HFS-009, College Park, MD, 20740-3835, (888) 723-3366, https://www.fda.gov .
Margaret Alic, PhD