37 Clinical Trials for Various Conditions
Long-chain cyclopropane fatty acids (CpFAs) are microbially-derived lipids (fats), some of which can be found in select foods and appear to be produced naturally in the gut from dietary fatty acid precursors. Some of these lipids appear to have signaling properties in the body's tissues, i.e., to help regulate cardiometabolic health. Thus, increasing the bioavailability of CpFAs in humans may have utility to improve management of blood sugar and blood lipids, or to mitigate or prevent non-alcoholic fatty liver disease (NAFLD). This study is a proof-of-principle experiment in 10 subjects, to feed dietary fats thought to enhance upper gut CpFA production. The latter will be monitored through post-meal blood and urine CpFA concentration measurements, as well as concentration in the stool.
Skeletal muscle burns a significant amount of the fat and sugar that circulates in the blood stream. Ideally, when sugar is elevated in the blood stream, the muscle will either use it to make new energy or store it for later use. Likewise, for fatty acids. Skeletal muscle of obese and diabetic humans has been shown to inadequately use either sugar or fatty acids when they increase in the blood stream, and this has been termed metabolic inflexibility. The cause of metabolic inflexibility is not known, but it is believed that eating more fat than the body needs for energy may be a contributing factor. Metabolic inflexibility in skeletal muscle is bad because if the muscle does not use the sugar or fat, it will be stored elsewhere in the body and potentially lead to obesity and the resistance to insulin. The investigators have performed a research study with nonobese, healthy humans during which we fed them a high fat diet for 5 days. Interesting, only 5 days of a high fat diet is sufficient to cause the skeletal muscle to become metabolically inflexible just like that observed in obese and diabetic humans. The investigators are proposing addition studies to feed healthy humans a high fat diet for 5 days in effort to better understand what causes metabolic flexibility. The investigators are speculating that a high fat diet causes the intestines to release a substance called endotoxin that causes muscle to become metabolically inflexible. The investigators will test this notion in our proposed studies.
Generally, people with low levels of high-density lipoprotein (HDL) in blood are more likely to get heart disease than those who have normal or high levels. Dietary fat, whether the harmful type (saturated) or beneficial type (unsaturated) raises HDL levels. Dietary carbohydrate lowers HDL. The investigators are doing this research study to find out why the amount of HDL in a person's blood is affected by dietary unsaturated fat and carbohydrate. The investigators will trace the ability of the HDL in a person's blood to take up cholesterol, get bigger, and then leave the blood by passing into the liver. The investigators want to know if dietary unsaturated fat improves the ability of HDL to do this compared to dietary carbohydrate.
This study is designed to determine if the amount of fat and saturated fat in the diet contributes to the development of a condition called fatty liver disease in the absence of changes in weight.
This study is being conducted to learn more about the role of diet and exercise in regulating plasma triglyceride (fat) metabolism. The investigators will examine the effect of acute (24 hour) changes in energy intake and expenditure on fat metabolism the following day.
The purpose of this investigation was to examine the acute effects of consuming two different fitness drink formulas on the physiological response at rest and to exercise in healthy men and women.
The rapidly rising risk of gestational diabetes pregnant women demands that an effective diet strategy be developed due to the high risk of fetal overgrowth, which places the newborn at increased risk for childhood obesity and metabolic syndrome. The aims of this randomized clinical trial are to compare the effects of an 8-wk isocaloric higher complex carbohydrate/lower fat diet vs. a conventional lower carbohydrate (higher fat) diet on glycemic and lipid profiles, maternal insulin resistance, placenta nutrient transporters, the maternal microbiome, neonatal intrahepatic fat, and neonatal total adiposity (primary outcome). The investigators will then follow the infants for 1-yr and measure maternal breast milk and infant microbiome composition to observe if they impact net fat mass gain differently in infants exposed to one diet vs. the other. Identifying a diet for gestational diabetes mellitus women that can effectively alter maternal/fetal metabolism is critical to reducing short- and long-term metabolic risk in this growing cohort of mothers and infants and has the potential to be applicable to overweight/obese pregnant women.
The purpose of this study is to compare the effect of ingesting caffeine and mixed flavonoids (4 capsules, split between breakfast and lunch) on energy expenditure and fat oxidation in a metabolic chamber with 20 women (non-obese, healthy, ages 20-47 years, pre-menopausal). We hypothesize that based on the existing literature, ingestion of a double dose of the caffeine-mixed flavonoid supplement compared to placebo will increase fat oxidation and increase 24 h energy expenditure by about 75 kilocalories.
The purpose of this study is to see how adding avocado to a breakfast meal affects blood sugar control and signals of hunger and fullness after eating. The investigators will test the effects of 3 breakfast meals on blood sugar control and signals of hunger and fullness after eating: 1. Whole-wheat bread and strawberry jam 2. Whole-wheat bread, strawberry jam, and avocado 3. Whole-wheat bread and strawberry jam (meal enriched with fat and fiber to mimic that of an avocado) Participants will undergo 3 test periods, each separated by a week. Each test period consists of one day with set meals that the investigators will provide (breakfast, lunch, and dinner), and then the next morning, participants will eat a breakfast meal and have blood drawn several times over 4 hours.
Background: At least 30% of Americans have fatty liver disease. This means that they store too much fat in the liver. At the moment lifestyle changes are the only way to treat this problem. Objective: To test how (1) a low-carbohydrate diet and (2) a supplement called nicotinamide riboside (NR) affect how a person s body uses dietary fat. Eligibility: Men aged 18 to 65 and women aged 18 to 50 who are healthy volunteers with a body mass index (height to weight ratio) of 25 or more. Adults with maturity-onset diabetes of the young type 2 (MODY2) are also needed. Design: Participants with diabetes will have 1 screening visit and a 9-day clinic stay. Healthy volunteers will have 1 screening visit and 2 clinic stays of 1 to 2 weeks each. During screening, all participants will have a physical exam with blood and urine tests. They will have their heart rhythm measured while riding a gym bike. NR is a pill taken by mouth. Only healthy volunteers will take the NR, for 14 days at a time, during 1 clinic stay. During their other stay, they will take placebos; these are pills that look like the study supplement but contain no NR. During each clinic stay, all participants will eat a normal American diet. Then they will eat a ketogenic "low-carb" diet for 5 days. Participants will have many tests, including: Sleeping every night and having two 24-hour stays in a special room that measures the gases their body uses and produces. Drinking a high-fat shake, then remaining seated for 5 hours while their blood and breath are monitored. Having a substance injected into the arm and remaining seated for 3 hours while their blood is measured. Wearing monitors to measure their activity levels. Another monitor will measure their blood glucose levels. Having imaging scans. ...
Two-arm, parallel design with children between the ages of 10 - 18 with obesity and metabolic syndrome randomized (15 per group) to reduced-carbohydrate diet or a reduced-fat diet for 8 weeks.
Individuals have a significant capacity to adapt to different environments by changing their core metabolic pathways. This adaptation is especially important in regards to diet. Epidemiological research over the last several decades have shown that diets high in saturated fats have a greater ability to cause insulin resistance and the 'metabolic syndrome' while diets low in saturated fats (or a so called 'Mediterranean Diet), reduces the risk for cardiovascular disease. In humans, experimental diets high in unsaturated fats, as compared to high carbohydrate or high saturated fat diets, result in increased insulin sensitivity and improved lipid profiles. In this application, the investigators propose to systematically assess the effects of two diets enriched in either saturated or unsaturated fatty acids and determine the cellular and molecular mechanisms of the apparent increase in insulin sensitivity. The investigators hypothesize that individuals will 'adapt' to the different diets and the investigators will be able to generate predictive alterations in gene expression and metabolites that underlie the alterations in metabolism. In parallel, the investigators will test the ability of these different diets to affect the release of gastrointestinal hormones that may be critical to modulation of appetite.
The metabolic syndrome consists of five concurrent conditions which increase risk of heart disease, stroke, and diabetes. Persons with the metabolic syndrome usually have high triglyceride and low HDL levels and are overweight. Low fat, high carbohydrate diets may not provide the same cholesterol-lowering benefits to obese individuals as they do to non-obese individuals. The purpose of this study is to compare the effects of a low fat, high carbohydrate diet versus a moderate fat, moderate carbohydrate diet on the heart, blood vessels, and cholesterol levels in individuals with metabolic syndrome.
The purpose of this trial is to study the safety, tolerability and efficacy of an almond enriched hypocaloric diet on weight loss and weight maintenance, as well as on established and emerging cardiovascular risk factors in approximately 112 overweight and obese persons.
Determine whether the mid-day suppression of hunger and amplified increase in the release of glucose-dependent insulinotropic peptide (GIP) and glucagon-like peptide 1 (GLP-1) following morning exercise is due to increased fat content of the diet per se or a combination of high fat diet after morning exercise. The action of gut peptides, particularly GLP-1, on gastric emptying is likely to be important in mediating its effects on postprandial appetite and glycemia (Nauck et al. 1997). Our hypothesis is that exercise amplifies gut peptide secretion when diet is enriched with fat, and that this stimulus suppresses the hunger sensation.
This is a pilot study in 10 men to test the hypothesis that perturbations in substrate flux and the circulating metabolic and pro-inflammatory milieus during a high-fat diet paradigm will modulate DNA methylation of genes in sperm associated with obesity and cardiometabolic dysfunction.
In this research study, investigators will test the effects of an approved medication for diabetes,Liraglutide, to reduce insulin resistance that develops from eating a diet high in saturated fats.
Type 2 diabetes is more frequent in Japanese Americans than in Japan or the U.S. non-Hispanic white population. This appears to be due to the effects of ''westernization'' to bring out metabolic changes that lead to diabetes. This study will look at whether increased physical activity and dietary changes will reduce or prevent the metabolic changes that lead to type 2 diabetes in Japanese Americans who have impaired glucose tolerance, a condition intermediate between normal glucose tolerance and diabetes.
This randomized, cross-over trial aims to assess changes in body weight, plasma lipids, insulin sensitivity, and postprandial metabolism with a low-fat, plant-based diet and a Mediterranean diet, both followed for 4 months.
This study investigates the effects of bioactive fatty acids in full fat dairy (whole yogurt), on insulin action, calorie needs, blood lipids, immune function, and body composition in normal and overweight male and female volunteers.
This study will try to determine if intake of dietary fats or carbohydrates influences the tendency to gain weight or accumulate body fat. It will examine how the hormones that regulate weight may change with a shift from a balanced diet to one that is low in fat or carbohydrate, irrespective of caloric intake. Men and women between the ages of 18 and 40 years with a body mass index of 30 to 49 kg/m2 may be eligible for this study. Candidates will be screened with a history, physical examination, blood tests and questionnaires regarding activity, prior diets, and eating patterns. Participants will follow two separate diet regimens for 5 days each. The first will be a balanced diet, and the second will be either a low-fat/high-carbohydrate diet or a low-carbohydrate/high-fat diet. The diets are not designed to produce weight loss. Participants will receive all their meals and snacks for the two diets from the National Institutes of Health and, for the first 3 days of each diet, will be seen as outpatients. For days 4 and 5 of each diet, they will be admitted to the Clinical Center and will undergo the following procedures: * Blood tests - Blood samples will be collected every 30 minutes over a 24-hour period through an indwelling catheter in the arm. A total of about 15 tablespoons will be drawn for each of the two diets. * 24-hour urine collection - One 24 hour urine collection will be done at home the day before admission to the Clinical Center, and the other will be done during the hospital stay. * Urinalysis and pregnancy test - A small urine sample will be taken and women will provide an additional sample for a pregnancy test. * Body measurements - Height and weight will be measured using scales. Body fat will be measured by two methods: skin fold thickness, measured with calipers in 5 separate places; and body circumference measurements, in which body parts are measured with a tape measure. * Bod pod measurement - Proportions of fat and non-fat tissue in body weight are measured while the participant sits in a capsule-like device for 5 minutes. * Bioelectric impedance analysis - Proportions of body fat are measured based on conduction of a small electric current. * Total body water estimate -The proportion of body weight that is water is determined, using a method that involves drinking a cup of a special kind of "heavy" water (deuterium) and then measuring the amount of heavy water in a urine sample taken after 4 hours. * Exercise - Participants will maintain their usual exercise routine, as it was before beginning the study.
Background: Researchers want to learn how different diets affect hormone levels, body weight, energy expenditure, liver fat, and more. To do this, they will use specialized techniques and food plans. This is not a weight loss study. Objective: To better understand how low-fat and low-carbohydrate foods affect health. Eligibility: Men and women ages 18-50 who have a stable body weight and can exercise daily Design: Participants will have a screening visit that lasts 4-6 hours. It will include: Medical history Physical exam Fasting blood and urine tests Questionnaires Trying foods from the study Participants will be admitted to the Clinical Center and will stay for 4 weeks without leaving. They can have visitors. Participants will wear activity and glucose monitors throughout the study. They will be weighed daily and will complete daily exercise. They will eat 3 meals daily, plus snacks. They will give urine, saliva, and blood samples. They will fill out questionnaires and rate their hunger, appetite, and sense of taste. They will have body scans. For the scans, they will lie in a machine that takes X-ray pictures of the body. Participants will complete activities to measure how many calories they burn and how the diets affect them: Participants will drink special liquids to measure calories burned, sugar, and sense of taste. Participants will wear a plastic hood while resting. Participants will stay alone in a special room for 24 hours. Participants will eat a low-carb, high-fat diet for 2 weeks and a high-carb, low-fat diet for 2 weeks. Participants may be dismissed if they purposefully use the study to try to change their body weight. Sponsoring Institution: National Institute of Diabetes and Digestive and Kidney Diseases ...
The purpose of this study is to understand how weight loss by a very low fat plant-based diet with an exercise program affects metabolic and cardiovascular health in overweight adults at high risk for disease. Outcome measures will include assessment of insulin sensitivity, β-cell function, body fat distribution, skeletal muscle and adipose tissue biology, cardiovascular function, cardiorespiratory fitness, muscular strength, immune function, and the gut microbiome.
This study evaluates whether a diet rich in poly-unsaturated fats can compensate for the negative effects of high saturated fat meals on metabolic, inflammatory, and coagulation responses. Half of the participants will receive a high polyunsaturated fat diet )50% carbohydrate, 15% protein, and 35% fat. 21% of total energy will be poly-unsaturated fatty acids, 9% mono-unsaturated fatty acids, and 5% saturated fatty acids) for 7 days, while the other half will receive a control diet 50% carbohydrate, 35% fat, and 15% protein 50% carbohydrate, 35% fat, and 15% protein. Only, 7% of total energy will be poly-unsaturated fatty acids, 15% of total energy will be mono-unsaturated fatty acids, and 13% of total energy will be saturated fatty acids.) for 7 days.
The purpose of this study is to assess the effectiveness of two different reduced calorie diets that have different combinations of carbohydrate, fat, and protein content in 2 groups of study participants: insulin sensitive participants and insulin resistant participants. The hypothesis of the study is that people with high and low levels of insulin resistance may respond differently to different diet compositions in a real-world environment using meals that are commonly available.
Protocol Number: 22DK0002 Title: Effects of Ultra-processed versus Unprocessed Diets on Energy Metabolism Background: Many diets worldwide include both processed and unprocessed foods. Researchers want to study the effects these foods have on a person s health. Objective: To study how different diets affect a person s health and metabolism. Eligibility: Adults aged 18 60 without diabetes who have stable weight and can exercise. Design: Participants will be screened with: Medical history Physical exam Heart tests Resting energy expenditure (to determine calorie needs) Blood and urine tests 20-minute stationary bicycle session Food, diet, and mental health questionnaires Participants will stay at NIH for 4 weeks. They will receive 3 meals a day and may eat as little or as much as they want. The diet will change each week. Their weight will be recorded daily. They will ride a stationary bicycle daily. Each week, they will do the following: Spend 1 day in a special room that assesses their metabolism Have 24-hour urine collections Give skin and fecal samples Repeat some screening tests Have scans to measure body fat Complete computerized behavior tasks Wear an activity monitor to track physical activity Wear a glucose monitor. A sensor will be inserted under the skin with a small needle. It will be replaced weekly. Take taste tests. They will swish water and flavored liquids around in their mouth and pick which ones had a non-neutral taste. They will also compare liquids for which ones taste better. Participation will last for 4 weeks. Sponsoring Institution: National Institute of Diabetes and Digestive and Kidney Diseases ...
The study team will examine the effect of a ketogenic diet alone and ketogenic diet supplemented with oral ketones on how the body of individuals with type 2 diabetes respond to insulin, regulates insulin secretion, food intake and energetic pathways and influences body fat distribution.
This study determines if substituting full-fat yogurt (i.e., whole, 3.25% fat) for non-fat yogurt in the diet can reduce the risk of type 2 diabetes and inflammation in association with changes in the composition of the gastrointestinal bacteria prediabetic male and female volunteers. The central hypothesis is that dairy fat impacts whole body glucose handling and insulin sensitivity as well as inflammation both directly, and indirectly via influencing the gut microbiota composition.
The Habitual Diet and Avocado Trial will evaluate the effects of providing one avocado per day for recommended consumption over a 6 month period in a cohort of approximately 1000 free-living participants with increased waist circumference in comparison with a control group that will maintain their habitual diets. Participants will be recruited and screened at 4 clinics in 4 locations: Pennsylvania State University; Loma Linda University; UCLA, and Tufts University (250 per site).
The purpose of this study is to determine the effects of change in diet quality (carbohydrate restriction versus fat restriction) on body composition, fat distribution, cardiometabolic risk factors, physical function, and quality of life in aging adults with obesity.