Digital therapeutics (DTx) are emerging as a novel solution to improve lifestyle and prevent non-communicable diseases. Obesity is a complex, multi-factorial, chronic condition that requires patient-centered lifestyle modification. DTx, such as mobile applications and wearables, may offer easily accessible, efficient, and personalized care in the field of obesity and metabolic diseases. Yet, there is controversy over its clinical usefulness. This review will provide a comprehensive overview of DTx, including its potential role and current limitation in obesity care, based on recent literature.

While the rising epidemic of obesity is primarily attributed to a sedentary lifestyle, poor dietary habits, and the aging of the population, secondary causes of obesity generally go undetected and untreated. These include endocrinological disorders, such as Cushing's syndrome, polycystic ovary syndrome, hypothalamic obesity, hypogonadism, and hypothyroidism, as well as genetic, syndromic, and drug-related obesity. We present an overview of the major disorders associated with obesity, highlighting the pathophysiologic mechanisms and discussing the diagnostic and treatment strategies that are most helpful to practicing physicians in recognizing and treating these generally under-detected and undertreated disorders.

Obesity is a serious health concern, which has been linked to an increased risk for cardiovascular diseases and some cancers. The traditional obesity control program is expensive. Moreover, it is difficult to maintain a healthy body weight as well as reduce body fat. The long-term use of effective and tolerable medication is carefully recommended to control body weight. In addition to obesity control medications, health functional foods, related to body weight control, have become popular in the commercial market. Known mechanisms include lipolysis, appetite control, inflammation reduction, and lean body mass maintenance. Previous clinical trials have documented the efficacy of some health functional foods; however, there are limitations. Studies on the potential roles and efficacy of some health functional foods, including caffeine, green tea, protein supplement, probiotics, and arginine, were reviewed. More large-scale and randomized placebo-controlled trials should be conducted eventually.

Obesity is an increasing public health and medical issue worldwide. It has been associated with several comorbidities, including diabetes, cardiovascular disease, stroke, and cancer. Chronic kidney disease (CKD) is another important comorbidity of obesity. Other major causes of CKD include hypertension and diabetes. However, the association between obesity and CKD is often overlooked. Among patients with CKD, patients with obesity were more vulnerable to have rapid kidney function decline than that of those with normal weight. Additionally, CKD is more prevalent among patients with obesity. These aggravations are induced through multiple mechanisms, specifically metabolic impairment of obesity and mechanical burden because of increasing intraabdominal renal pressure. Furthermore, the inflammation and lipotoxicity, caused by obesity, are critical in the CKD aggravation in patients with obesity. To prevent this, all adult patients with obesity are tested for CKD. The workup includes the estimated glomerular filtration rate and regular follow-up. Step-wise management is required for patients with obesity with CKD. Prompt reduction and management of obesity effectively delay CKD progression among patients with obesity and CKD. Therefore, weight loss is a core management for patients with obesity and CKD. Based on several studies, this article focused on the association between CKD and obesity, as well as the diagnosis and weight management of patients with obesity and CKD.

Treatment of obesity includes diet therapy, exercise therapy, cognitive behavioral therapy, drug therapy, and bariatric surgery. Most obese patients lose weight by combining diet, exercise, cognitive behavioral therapy or medication. But, in some cases, only one of these treatments is preferred. A 56-year-old male patient had a body mass index (BMI) of 33.1 kg/m² and a waist circumference of 108 cm. He had been treated for hypertension; diabetes and dyslipidemia were diagnosed but not treated. However, at the initial visit to treat obesity, he was diagnosed with type 2 diabetes mellitus and dyslipidemia again. So he decided to treat these two diseases with drugs first and modify his lifestyle. He started walking more than 20,000 steps every day and then he really walked about 15,000 steps every day during 5 months, although diet calorie or alcohol drinking amount was not significantly decreased. After about 6 months, the patient's weight decreased by 10.1 kg, the BMI decreased by 4.1 kg/m², the waist circumference decreased by 10 cm, the glycated hemoglobin (HbA1c) decreased by 4.59%, the visceral fat area decreased by 115 cm², and the subcutaneous fat decreased by 38 cm². As a result of body composition analysis, muscle mass increased by 1.2 kg, and the percentage of body fat decreased by 10.4%. The walking exercise does not have any space restrictions and has high accessibility by using a mobile phone app. Therefore, considering the patient's situation, it would be better to treat obese patients by first recommending walking exercises and increasing the number of steps to lose weight and improve the comorbidities.

Liraglutide (Saxenda^R) is prescribed to induce and sustain weight loss in obese patients. The starting dose of liraglutide is 0.6 mg/day for 1 week, which is increased by 0.6 mg/day every week until the full maintenance dose of 3 mg/day is achieved. Such dose titration is needed to prevent side effects, which primarily include gastrointestinal problems such as nausea, diarrhea, constipation, vomiting, dyspepsia, and abdominal pain. A 35-year-old, reportedly healthy obese man receiving liraglutide treatment for obesity visited the emergency room complaining of generalized weakness and dizziness accompanied by repeated diarrhea and vomiting. He reported over 20 episodes of diarrhea starting the day after liraglutide dose escalation from 1.2 mg/day to 1.8 mg/day. Laboratory findings suggested pre-renal acute kidney injury, including serum creatinine 4.77 mg/dl, blood urea nitrogen (BUN) 37 mg/dl, estimated glomerular filtration rate (eGFR) 15 ml/min/1.73 m², and Fractional excretion of sodium 0.08. After volume repletion therapy, his renal function recovered to a normal range with laboratory values of creatinine 1.08 mg/dl, BUN 14 mg/dl, and eGFR 88 ml/min/1.73 m². This case emphasizes the need for caution when prescribing glucagon-like peptide-1 receptor agonists, including liraglutide, given the risk of serious renal impairments induced by volume depletion and dehydration through severe-grade diarrhea and vomiting.

Obesity increases the risk of developing metabolic diseases such as hypertension, type 2 diabetes, hyperlipidemia, and cardiovascular diseases, as well as some cancers. To prevent the occurrence of these diseases and death, it is essential to manage obesity. Though there are several treatments for obesity, lifestyle interventions, such as diet and exercise, and drug therapy are most widely used in clinical practice. Among the anti-obesity drugs available, the weight loss effect of naltrexone/bupropion has been well-proven. We present a case study in which naltrexone/bupropion, a glucagon-like peptide-1 agonist, and a sodium-glucose transporter 2 inhibitor showed significant weight loss and improved metabolic parameters. Additionally, the management of type 2 diabetes and hypertension, which are common diseases in patients with obesity, was also included.