Corby Martin

Pennington Biomedical Research Center · Ingestive Behavior, Weight Management and Health Promotion

BACKGROUND: Low income and low health literacy are associated with poorer health knowledge, health behaviors and poor health outcomes. The effectiveness of health literacy-directed weight loss treatment interventions in primary care clinics is lacking. OBJECTIVE: The aim of this study was to conduct a pragmatic cluster-randomized trial (PROmoting...

Objective Bariatric surgery remains the most effective treatment to achieve substantial weight loss; however, total daily energy expenditure and physical activity changes in response to such interventions have been seldom explored. Methods In this prospective observational study, total daily energy expenditure (TDEE) using doubly labeled water and...

Rationale Short‐term weight loss is possible in a variety of settings. However, long‐term, free‐living weight loss maintenance following structured weight loss interventions remains elusive. Objective The purpose was to study body weight trajectories over 2 years of intensive lifestyle intervention (ILI) and up to 4 years of follow‐up versus usual...

Background Whole food plant-based diet (WFPBD), minimally processed foods with limited consumption of animal products, is associated with improved health outcomes. The benefits of WFPBD are underexplored in individuals with type 1 diabetes (T1D). The primary objective of this analysis is to evaluate the association between WFPBD on glycemia in indi...

Purpose American College of Sports Medicine (ACSM) metabolic equations are used to estimate energy expenditure (EE) of physical activity and prescribe aerobic exercise to meet EE requirements. Limited evidence supports their accuracy in sedentary adults with overweight or obesity during controlled exercise interventions. The purpose of this study w...

PURPOSE: Some evidence shows greater peak oxygen uptake (VO2peak) is associated with greater resting metabolic rate, but the relationship between VO2peak and food intake has not been systematically examined using gold standard assessments of energy intake. This analysis aimed to examine the association between VO2peak and energy intake, macronutrie...

BACKGROUND: Predicting individual weight loss responses to lifestyle interventions is challenging but might help practitioners and clinicians select the most promising approach for each individual. OBJECTIVE: The primary aim of this study was to develop machine learning models to predict individual weight loss responses using only variables known b...

The characterization of human behavior in real-world contexts is critical for developing a comprehensive model of human health. Recent technological advancements have enabled wearables and sensors to passively and unobtrusively record and presumably quantify human behavior. Better understanding human activities in unobtrusive and passive ways is an...

The prevalence of pediatric obesity has increased over the past 40 years and the prevalence in 6 to 19 years old is currently over 20%. This increase in obesity is predicted to negatively impact health and result in multiple obesity-related comorbidities in adulthood. Taste and food preferences are complex, and understanding the potential driving f...

BACKGROUND: Weight control is a common motive for continued cigarette smoking, and weight concerns pose a barrier to quitting, with effects driven in part by nicotine’s ability to reduce appetite and ultimately body weight. While there are similar perceptions regarding electronic nicotine delivery systems (ENDS) for weight control among current use...

SIGNIFICANCE: Electronic Nicotine Delivery Systems (ENDS) contain a heater that aerosolizes liquid that is inhaled. ENDS liquids usually contain nicotine, and nicotine content varies among liquids. Remotely and accurately quantifying the nicotine content of liquids and liquid intake is difficult. eCigTracker is a smartphone app that aims to accurat...

Aims/hypothesis Adults with type 1 diabetes should perform daily physical activity to help maintain health and fitness, but the influence of daily step counts on continuous glucose monitoring (CGM) metrics are unclear. This analysis used the Type 1 Diabetes Exercise Initiative (T1DEXI) dataset to investigate the effect of daily step count on CGM-ba...

Caloric restriction (CR) modifies lifespan and aging biology in animal models. The Comprehensive Assessment of Long‐Term Effects of Reducing Intake of Energy (CALERIE™) 2 trial tested translation of these findings to humans. CALERIE™ randomized healthy, nonobese men and premenopausal women (age 21–50y; BMI 22.0–27.9 kg/m²), to 25% CR or ad‐libitum...

Aims To evaluate factors affecting within-participant reproducibility in glycemic response to different forms of exercise. Methods Structured exercise sessions ~30 minutes in length from the Type 1 Diabetes Exercise Initiative (T1DEXI) study were used to assess within-participant glycemic variability during and after exercise. The effect of severa...

Objective To assess whether impaired awareness of hypoglycemia (IAH) affects exercise-associated hypoglycemia in adults with type 1 diabetes (T1D). Methods We compared continuous glucose monitoring (CGM)-measured glucose during exercise and for 24-hours following exercise from 95 adults with T1D and IAH (Clarke score ≥4 or ≥1 severe hypoglycemic e...

Background The amount and type of food consumed impacts the glycemic response and insulin needs of people with type 1 diabetes mellitus (T1DM). Daily variability in consumption, reflected in diet quality, may acutely impact glycemic levels and insulin needs. Objective Type 1 Diabetes Exercise Initiative (T1DEXI) data were examined to evaluate the...

Background: Managing exercise in type 1 diabetes is challenging, in part, because different types of exercises can have diverging effects on glycemia. The aim of this work was to develop a classification model that can classify an exercise event (structured or unstructured) as aerobic, interval, or resistance for the purpose of incorporation into a...

CONTEXT: Exercise can decrease central adiposity, but the effect of exercise dose and the relationship between central adiposity and exercise-induced compensation is unclear. OBJECTIVE: Test the effect of exercise dose on central adiposity change and the association between central adiposity and exercise-induced weight compensation. METHODS: In t...

Previous work has aimed to disentangle the acute effects of nicotine and smoking on appetite with mixed findings. Electronic nicotine delivery systems (ENDS) have yet to be examined in this regard despite evidence of use for weight control. The present study tested the influence of an ENDS on acute energy intake and associated subjective effects. P...

Given prior literature focused on the Developmental Origins of Health and Disease framework, there is strong rationale to hypothesize that reducing depression in the prenatal period will cause improvements in offspring cardiometabolic health. The current review outlines evidence that prenatal depression is associated with offspring cardiometabolic...

We explored the association between macronutrient intake and postprandial glucose variability in a large sample of youth living with T1D and consuming free-living meals. In the Type 1 Diabetes Exercise Initiative Pediatric (T1DEXIP) Study, youth took photographs before and after their meals on 3 days during a 10 day observation period. We used the...

Background Intranasal insulin is a promising treatment for cognitive decline in Alzheimer’s Disease (AD) and mild cognitive impairment (MCI). However, intranasal insulin has been shown to promote weight loss, leading to concerns about decreased appetite, decreased food intake, and unintentional weight loss as negative side effects among metabolic a...

Objective Studies have consistently shown that African American individuals lose less weight in response to behavioral interventions, but the mechanisms leading to this result have been understudied. Methods Data were derived from the PROmoting Successful Weight Loss in Primary CarE in Louisiana (PROPEL) study, which was a cluster‐randomized, two‐...

Intensive lifestyle interventions are the first-line approach to effectively treat obesity, typically relying on in-person contact between patients and interventionists. However, several barriers exist to in-person obesity treatment, including travel time, cost, scheduling conflicts, and the burden of attending in-person sessions. Remotely delivere...

Calorie restriction (CR) with adequate nutrient intake is a potential geroprotective intervention. To advance this concept in humans, we tested the hypothesis that moderate CR in healthy young‐to‐middle‐aged individuals would reduce circulating biomarkers of cellular senescence, a fundamental mechanism of aging and aging‐related conditions. Using p...

The lifespan extension induced by 40% caloric restriction (CR) in rodents is accompanied by postponement of disease, preservation of function, and increased stress resistance. Whether CR elicits the same physiological and molecular responses in humans remains mostly unexplored. In the CALERIE study, 12% CR for 2 years in healthy humans induced mino...

Weight loss (WL) differences between isocaloric high-carbohydrate and high-fat diets are generally small; however, individual WL varies within diet groups. Genotype patterns may modify diet effects, with carbohydrate-responsive genotypes losing more weight on high-carbohydrate diets (and vice versa for fat-responsive genotypes). We investigated whe...

Objective Nocturnal hypoglycemia is a known challenge for people with type 1 diabetes, especially for physically active individuals or those on multiple daily injections. We developed an evidential neural network (ENN) to predict at bedtime the probability and timing of nocturnal hypoglycemia (0-4 vs 4-8 h after bedtime) based on several glucose me...

Objective This study's objective was to develop models predicting the relative reduction in skeletal muscle (SM) mass during periods of voluntary calorie restriction (CR) and to validate model predictions in longitudinally monitored samples. Methods The model development group included healthy nonexercising adults ( n = 897) who had whole‐body SM...

Older adults lose more weight during diet-based lifestyle interventions, possibly because of increased reductions in lean mass and food intake. However, it is not known if age is associated with weight and body composition change during exercise training. The primary aim of this analysis was to test if age was associated with changes in body weight...

Background The commercial application Openfit allows for automatic identification and quantification of food intake through short video capture without a physical reference marker. There are no known peer-reviewed publications on the validity of this Nutrition Artificial Intelligence (AI). Objectives To test the validity of Openfit to identify foo...

OBJECTIVE: This study tested whether initial weight change (WC), self-weighing, and adherence to the expected WC trajectory predict longer-term WC in an underserved primary-care population with obesity. METHODS: Data from the intervention group (n = 452; 88% women; 74% Black; BMI 37.3 kg/m2 [SD: 4.6]) of the Promoting Successful Weight Loss in P...

BACKGROUND: Currently there are limited data as to whether dietary intake can be improved during pragmatic weight loss interventions in primary care in underserved individuals. METHODS: Patients with obesity were recruited into the PROPEL trial, which randomized 18 clinics to either an intensive lifestyle intervention (ILI) or usual care (UC). A...

The Eating Disorders In weight-related Therapy (EDIT) Collaboration brings together data from randomised controlled trials of behavioural weight management interventions to identify individual participant risk factors and intervention strategies that contribute to eating disorder risk. We present a protocol for a systematic review and individual pa...

The amount and type of food consumed impacts glycemic response and insulin needs of people with type 1 diabetes (T1D). Day to day variation in types of foods consumed or diet quality may acutely impact glycemic levels and insulin needs within an individual with T1D. As part of the Type 1 Diabetes Exercise Initiative (T1Dexi), we examined the impact...

Tirzepatide (TZP) promotes significant and clinically meaningful weight loss. In a randomized blinded clinical trial in people with obesity undergoing caloric restriction, we investigated the effect of TZP vs Placebo (PBO) on food intake during ad libitum lunch and dinner, appetite, food preference and craving. In this 18wk phase 1 study, 55 people...

Prior exposure to hypoglycemia and exercise may each dampen the sympathoadrenal response to subsequent hypoglycemia, leading to impaired awareness of hypoglycemia (IAH) and increased risk for experiencing clinically significant hypoglycemia. Whether glucose changes during exercise differ in those with IAH vs. intact awareness of hypoglycemia (Aware...

Objective: Exercise is known to increase the risk for hypoglycemia in type 1 diabetes but predicting when it may occur remains a major challenge. The objective of this study was to develop a hypoglycemia prediction model based on a large real-world study of exercise in type 1 diabetes. Research design and methods: Structured study-specified exer...

Obesity is caused by a prolonged positive energy balance1,2. Whether reduced energy expenditure stemming from reduced activity levels contributes is debated3,4. Here we show that in both sexes, total energy expenditure (TEE) adjusted for body composition and age declined since the late 1980s, while adjusted activity energy expenditure increased ove...

Background The objective was to test the efficacy of a scalable, virtually delivered, diabetes-tailored weight management program on glycemic control in adults with type 2 diabetes (T2D). Methods This was a single arm, three-site clinical trial. Participants had baseline HbA1c between 7–11% and BMI between 27–50 kg/m². Primary outcome was change i...

Introduction: Clinically significant weight loss is associated with health benefits for overweight and obese adults. Participation in adequate amounts of physical activity is critical for weight maintenance. However, few studies in the literature have evaluated the amount of physical activity needed to promote weight maintenance in a supervised exe...

OBJECTIVE Maintenance of glycemic control during and after exercise remains a major challenge for individuals with type 1 diabetes. Glycemic responses to exercise may differ by exercise type (aerobic, interval, or resistance), and the effect of activity type on glycemic control after exercise remains unclear. RESEARCH DESIGN AND METHODS The Type 1...

The purpose of this study was to determine the association between changes in physical activity and changes in body weight in a cluster-randomized weight loss trial conducted in an underserved population in Louisiana. This study reports analyses conducted in the intervention group only, which was a 24-month multi-component weight loss program deliv...

The Eating Disorders In weight-related Therapy (EDIT) Collaboration brings together data from randomised controlled trials of behavioural weight management interventions to identify individual participant risk factors and intervention strategies that contribute to eating disorder risk. We present a protocol for a systematic review and individual pa...

Objective Data are mixed on whether intermittent fasting improves weight loss and cardiometabolic health. Here, the effects of time-restricted eating (TRE) in participants who consistently adhered ≥5 d/wk every week were analyzed. Methods Ninety patients aged 25 to 75 years old with obesity were randomized to early TRE (eTRE; 8-hour eating window...

Objective: Time-restricted eating (TRE) can reduce body weight, but it is unclear how it influences dietary patterns and behavior. Therefore, this study assessed the effects of TRE on diet quality, appetite, and several eating behaviors. Methods: Adults with obesity were randomized to early TRE plus energy restriction (eTRE + ER; 8-hour eating w...

BACKGROUND: Differences in weight loss between isocaloric high-carbohydrate and high-fat diets are generally small; however, weight loss responses vary within diet groups. Genotype patterns may modify the effects of diets, but findings are equivocal. We investigated whether weight loss on a diet concordant with one’s presumed genotype (fat-responsi...

Objective To determine the effect of a bundled intervention (home meal delivery and provision of cooking/serving resources) on preschoolers’ body mass index z-score (BMIz), dietary quality, and family meal frequency. Methods Participants (299 families; mean child age 4.4 years, 47% male, 55% White, 18% Black, 27% Hispanic or other race/ethnicity,...

Despite well-documented health benefits from exercise, a study on national trends in achieving the recommended minutes of physical activity guidelines has not improved since the guidelines were published in 2008. Peer interactions have been identified as a critical factor for increasing a population’s physical activity. The objective of this study...

In mammals, trait variation is often reported to be greater among males than females. However, to date, mainly only morphological traits have been studied. Energy expenditure represents the metabolic costs of multiple physical, physiological, and behavioral traits. Energy expenditure could exhibit particularly high greater male variation through a...

The ACSM metabolic equations have been used to estimate energy expenditure (EE) during exercise; yet limited evidence supports their accuracy in overweight/obese and sedentary individuals, especially during aerobic exercise training. PURPOSE: Evaluate the relationship between measured and estimated EE over a 24-wk exercise intervention and determi...

INTRODUCTION: Electronic cigarettes (ECIGs) heat a nicotine-containing liquid to produce an inhalable aerosol. ECIG power (wattage) and liquid nicotine concentration are two factors that predict nicotine emission rate (“flux”). These factors can vary greatly across devices and users. The purpose of this study was to examine ECIG device and liquid h...

Importance: It is unclear how effective intermittent fasting is for losing weight and body fat, and the effects may depend on the timing of the eating window. This randomized trial compared time-restricted eating (TRE) with eating over a period of 12 or more hours while matching weight-loss counseling across groups. Objective: To determine wheth...

Although many studies have assumed variability reflects variance caused by exercise training, few studies have examined whether interindividual differences in trainability are present following exercise training. The present individual participant data (IPD) meta-analysis sought to: (1) investigate the presence of interindividual differences in tra...

Background Smartphone-based methods are innovative and promising tools to accurately quantify energy intake (EI). The PortionSizeTM app measures dietary intake using embedded templates and provides real-time feedback. PortionSize also sends food images to a server where they can be analyzed using the Remote Food Photography Method (RFPM). The RFPM...

Background We developed the PortionSize™ app to provide users with real-time feedback on dietary intake including energy intake (kcal) and compliance to the United States Department of Agriculture (USDA) MyPlate recommendations. PortionSize relies on emerging technology (e.g., augmented reality) for portion size (gram weight) estimation. Currently,...

BACKGROUND: Intensive lifestyle interventions (ILIs) stimulate weight loss in underserved patients with obesity, but the mediators of weight change are unknown. OBJECTIVES: Identify the mediators of weight change during an ILI versus usual care (UC) in underserved patients with obesity. DESIGN: The Promoting Successful Weight Loss in Primary Car...

Lower ambient temperature (Ta) requires greater energy expenditure to sustain body temperature. However, effects of Ta on human energetics may be buffered by environmental modification and behavioral compensation. We used the IAEA DLW database for adults in the USA (n = 3213) to determine the effect of Ta (-10 to +30°C) on TEE, basal (BEE) and acti...

Background: Accurately assessing dietary intake can promote improved nutrition. The PortionSize app (Pennington Biomedical Research Center) was designed to quantify and provide real-time feedback on the intake of energy, food groups, saturated fat, and added sugar. Objective: This study aimed to assess the preliminary feasibility and validity of e...

Objectives We developed the PortionSizeTM app (PS) to estimate food intake and dietary adherence based on images of meals captured before and after eating occurs. The PS app provides real-time feedback to users about their dietary intake (energy, nutrients, and food groups) and adherence to specific diets. This pilot study provided initial tests of...

Objectives Over 26 million people in the United States have type 2 diabetes (T2D) and 89% of those living with diabetes have overweight or obesity. Weight loss improves glycemic control and scalable weight management programs tailored for those living with diabetes are critically needed. The objective of this trial was to test the efficacy of a sca...

Objectives We developed the PortionSizeTM app (PS app) to provide participants, in real time, an estimate of dietary intake and assistance with following dietary plans and managing body weight. The app provides templates superimposed on user's food images to provide feedback on energy intake (kcal), macronutrients, and food groups. The current pilo...

The proliferation of personal, household and workplace sensors and devices has created individual environments rich with purposeful and incidental feedback capable of altering behavior. We formulate an empirical learning model suitable for understanding individual behavioral responses in such environments. We estimate this model using data collecte...

The use of sensors available through smart devices has pervaded everyday life in several applications including human activity monitoring, healthcare, and social networks. In this study, we focus on the use of smartwatch accelerometer sensors to recognize eating activity. More specifically, we collected sensor data from 10 participants while consum...

Glycemic responses differ by exercise classification (i.e. aerobic, interval, resistance) in individuals with T1D, but the impact of insulin delivery modality (multiple daily injections [MDI], pump, closed loop) on these differences is unclear. Data from the Type 1 Diabetes Exercise Initiative study allowed us to compare glycemic responses by insul...

Different types of exercise (i.e., aerobic vs. interval vs. resistance) may have different immediate glycemic effects in adults with T1D, but the impact of exercise type on percent time in range 70-180 mg/dL (TIR) on physically active and inactive days is unknown. The Type 1 Diabetes Exercise Initiative (T1DEXI) study examined CGM data on active vs...

PURPOSE: Over 40% of adults in the United States have obesity. Obesity is associated with leading causes of preventable death, including heart disease, and psychosocial challenges, including lower quality of life (QOL). Weight loss of 5-10% of body weight significantly improves health and quality of life, though these findings are primarily derived...

Background/objectives: Pragmatic trials are increasingly used to study the implementation of weight loss interventions in real-world settings. This study compared researcher-measured body weights versus electronic medical record (EMR)-derived body weights from a pragmatic trial conducted in an underserved patient population. Subjects/methods: Th...

The prevalence of pediatric obesity has increased over the past 40 years and the rate in females 6 to 19 years old is currently over 19%. This profound increase in obesity is predicted to negatively impact health and result in multiple obesity-related comorbidities in adulthood. Obesity disproportionately affects ethnic minorities with a higher per...

Objectives The aim was to determine the nutritional adequacy of calorie restricted (CR) diets during CR interventions up to 12 months. Methods The Comprehensive Assessment of Long-Term Effects of Reducing Intake of Energy (CALERIE™) phase 1 trial consisted of 3 single-site studies to test the feasibility and effectiveness of CR in adults without o...

There is growing concern whether pro-environmental behavioral interventions can generate sufficient reductions in carbon emissions to address climate change. While many have suggested enhanced tailoring of interventions to increase effect sizes, and while individual tailoring is common among health interventions, little is known about how individua...

The aim of this study was to compute intra‐class correlations (ICCs) for weight‐related and patient‐reported outcomes in a cluster randomized clinical trial (cRCT) for weight loss. Baseline and follow‐up data from the Promoting Successful Weight Loss in Primary Care in Louisiana (PROPEL) cRCT were used in this analysis. ICCs were computed for basel...