WEIGHT LOSS

• Do not diet! - unfortunately, people often refer to healthy eating and weight loss as "going on a diet," implying it's a temporary measure to be stopped when they "go off a diet." The truth is achieving and maintaining a healthy weight means changing eating habits forever. Simply "going on a diet" for a set length of time with the mindset that it is punishment for past overeating will inevitably lead to failure. People who are serious about their emotional and physical health do not go on diets - they adopt healthy eating habits for life.


• Forget easy answers. They do not exist. - it's been said you will never go broke selling people easy answers, and nothing could be more true when it comes to weight loss. Billions of dollars are wasted every year on quick weight-loss diets, pills, potions, injections, creams, procedures, and promises. If you are ever tempted to fall for the next diet fad or product, ask yourself one question, "If it really worked, wouldn't everyone be skinny?"


• You are overweight because you consume more calories than you burn. - many overweight people assume they can't lose weight because they are different or something is wrong with them. The reality is we are all bound by the laws of physics, which only allow us to gain matter when we consume more energy than we burn.

• 1. Determine your normal body weight
• The most widely used measure is the body mass index (BMI)


• 2. Calculate your caloric needs
• Caloric needs are based on body weight and activity level. The links below offer several methods for calculating daily caloric needs.
• Detailed method - guide to calculating daily calorie requirements that incorporates time spent on specific activites
• Simple method - guide to calculating daily calorie requirements that uses a rough estimate of activity level
• Calorie calculator - calculator for determining the number of calories burned in a day based on activities performed


• 3. Calculate how many calories you should consume to lose weight
• Once you have figured out how many calories you use in a day, you will need to consume a deficit to lose weight
• In general, the following is true:
• A 500 calorie-a-day deficit for 7 days will lead to 1 pound of weight loss
• A 1000 calorie-a-day deficit for 7 days will lead to 2 pounds of weight loss, and so on
• Example:
• Tom calculates that he burns 2500 calories in a typical day
• If Tom consumes 2000 calories a day (500 calorie deficit) for one week, he can expect to lose 1 pound
• If Tom consumes 1500 calories a day (1000 calorie deficit) for one week, he can expect to lose 2 pounds
• Things to keep in mind:
• Exercise will greatly enhance your ability to achieve a caloric deficit
• As you lose weight, your basal energy expenditure will decrease, and you will have to increase activity and/or decrease calories to continue to lose weight


• 4. Avoid extreme eating habits and fads
• Diet fads and extreme eating habits rarely lead to prolonged, meaningful weight loss
• No diet that will "trick" your metabolism or lead to miraculous, enhanced weight loss
• Reviews of some popular diets are presented below


• 5. Calories, calories, calories!
• Diet theories come and go. For years we vilified fat then it was carbohydrates. Despite all this, studies have consistently shown that overall calorie consumption (regardless of the source) and energy expenditure are the main determinants of weight.
• Every weight loss plan should begin and end with monitoring the number of calories consumed
• It is easier today than ever to monitor calorie intake with food packaging guidelines and new laws that require restaurants to list calories


• 6. Know what you eat
• Read labels on everything you eat, including dressings, spreads, butter, creams, etc. You will be surprised to learn how many calories you may be adding to some foods.
• Replace high-calorie foods with low-calorie alternatives or reduce their intake
• A review of the different macronutrients can be found here - fats, carbohydrates, protein


• 7. Know how much you eat
• People who are serious about weight loss should buy a food scale and measure their serving sizes
• Portion control is an important part of weight loss. If you pour a big bowl of cereal or eat chips out of a bag, you may be getting 3 - 5 servings and 500 calories. Look at the label on what you are about to eat and weigh out a serving so that you know exactly where your calories are coming from.


• 8. Individualize your plan
• Diet programs come in all shapes and sizes, but costs, food preparation time, and palatability can make them difficult to maintain. Tailor your diet around foods you like and are willing to prepare. You do not have to give up foods you enjoy if you control your serving sizes and stay within your calorie goals.

• Normal body weight
• The first step in weight loss is determining an appropriate body weight. While an individual's perception of normal body weight is shaped by culture, environment, family, and friends, healthcare professionals categorize body weight based on mortality and disease risk. The most widely used method is the body mass index or BMI, a ratio of weight to height. While the BMI isn't perfect, studies have consistently shown it correlates well with disease risk and mortality.
• Normal weight ranges based on the BMI can be found by looking at a BMI chart - BMI chart (pdf)

• BMI calculators and charts are available at these links:
• Adult BMI calculator
• Child and teen BMI calculator
• BMI chart for adults
• The formula for calculating the BMI is as follows:

• BMI advantages
• The BMI is cheap, easy to measure, and has little interobserver variability
• It is a strong predictor of disease risk and mortality and performs well when compared to other body composition measures [1,2,3,4,5,6,7,8,9,12]

• BMI weaknesses
• Muscle mass
• The BMI cannot differentiate between muscle and fat, causing people with above-average muscle mass (e.g. weightlifters) to have higher BMIs that do not accurately reflect disease risk
• Elderly patients
• Some studies have found that elderly patients in the overweight range have lower mortality than normal-weight subjects [10,11]
• Ethnicity
• Some ethnicities have more muscle mass (e.g. Blacks) than others, altering the association between disease risk and BMI [13,14]

• Overview
• In the eighties and nineties, low-fat diets were popular. Then the pendulum shifted, and low-carb diets became the rage with the rediscovery of the Atkins diet. Four trials comparing low-carb to low-fat diets are detailed below, along with two meta-analyses on the topic.

• OBS
  Effects of Low-Carb vs Low-Fat Diets on Weight Loss and Cardiovascular Risk Factors, Archives of Internal Medicine meta-analysis (2006) [PubMed abstract]
• A meta-analysis in the Archives of IM looked at trials that compared low-fat to low-carb diets
• The analysis included 5 trials that encompassed 447 participants. Only 3 trials reported results at 12 months
• The analysis found the following:
• The low-carb diets lost significantly more weight at 6 months. At 12 months, the difference was not significant
• Difference in weight loss at 6 months (low-carb minus low-fat): 7.3 lbs, 95%CI [11.6 to 3.1]
• Difference in weight loss at 12 months (low-carb minus low-fat): 2.2 lbs, 95%CI [7.7 to -3.3] [38]
• Findings: Low-carbohydrate, non-energy-restricted diets appear to be at least as effective as low-fat, energy-restricted diets in inducing weight loss for up to 1 year. However, potential favorable changes in triglyceride and high-density lipoprotein cholesterol values should be weighed against potential unfavorable changes in low-density lipoprotein cholesterol values when low-carbohydrate diets to induce weight loss are considered.

• OBS
  Comparison of Weight Loss Among Named Diet Programs in Overweight and Obese Adults, JAMA meta-analysis (2014) [PubMed abstract]
• A network meta-analysis in the JAMA looked at randomized controlled trials that compared popular branded diets to alternatives
• Interventions were divided into 1 of 5 groups:
• 1. No diet
• 2. Moderate macronutrient (Biggest Loser, Jenny Craig, Nutrisystem, Volumetrics, Weight Watchers)
• 3. Low-carb (Atkins, South Beach, Zone)
• 4. Low-fat (Ornish, Rosemary Conley)
• 5. Usual care (LEARN diet)
• The primary outcome was weight loss and body mass index at 6- and 12-month follow-up (±3 months for both periods)
• Compared to no diet, the following was seen:
• Weight loss at 6 months: Low-carb diet - 19 lbs, Low-fat diet - 17.5 lbs, Moderate macronutrient diet - 15 lbs (low-carb vs macronutrient, p<0.05; low-carb vs low-fat, p> 0.05)
• Weight loss at 12 months: Low-carb diet - 16 lbs, Low-fat diet - 16 lbs, Moderate macronutrient diet - 12.5 lbs (low-carb vs macronutrient, p<0.05; low-carb vs low-fat, p> 0.05) [35]
• Findings: Significant weight loss was observed with any low-carbohydrate or low-fat diet. Weight loss differences between individual named diets were small. This supports the practice of recommending any diet that a patient will adhere to in order to lose weight.

• Summary
• Studies have consistently found no significant long-term difference in weight loss between low-carb and low-fat diets. In the short-term (up to 6 months), low-carb diets may cause slightly more weight loss, which may be due to water loss, as carbohydrate restriction leads to rapid depletion of muscle glycogen, a hydrophilic polysaccharide that attracts water.
• The energy expenditure study found that low-carb diets conferred a slightly higher resting energy expenditure than low-fat diets, although body weight did not differ significantly.

• Overview
• HCG (human chorionic gonadotropin) is a hormone released by the placenta in pregnant women. The HCG diet was developed in the 1950s by a British doctor named Simeons, who claimed that HCG injections alleviated hunger and mood problems in patients on very low-calorie diets (500 calories a day), leading to increased compliance and greater weight loss.
• The effects of the HCG diet were evaluated in the small placebo-controlled trial and meta-analysis detailed below

• RCT
  The Effect of HCG in the Treatment of Obesity by Means of the Simeons Therapy, Br J Clin Pharmacol (1995) [PubMed abstract]
• Researchers attempted to perform a meta-analysis on HCG studies in 1995 but were unable to find enough quality studies. Of the fourteen studies that ranked highest in their review, only two had an outcome in favor of the HCG diet.
• The authors concluded that HCG injections did not have a meaningful effect on weight loss [31]

• Summary
• There is no good evidence that HCG enhances weight loss or prevents hunger during dieting

• Overview
• Intermittent fasting has become a popular dieting method because it is easy to follow and may lead to reduced calorie intake. The first two studies below compared the effects of a calorie-restricted diet between patients who used intermittent fasting and those who did not. The third study compared intermittent fasting to usual eating without calorie restriction, and the fourth study compared intermittent fasting to a calorie-restricted diet and usual eating.

• RCT
  Intermittent Fasting vs None with a Calorie-Restricted Diet, JAMA Intern Med (2022) [PubMed abstract]
• Design: Randomized, controlled trial (N=90 | length = 14 weeks) in obese adults (average BMI 39.6)
• Treatment: Intermittent fasting (8-hour eating window from 7:00 to 15:00) vs Eating over a window of 12 hours or more (control group). All participants were counseled on consuming an energy-restricted diet.
• Primary outcomes: Weight loss and fat loss
• Results:
• Primary outcome (weight loss): Intermittent fasting - 13.9 lbs, Control - 8.8 lbs (p=0.002)
• Primary outcome (fat loss): Intermittent fasting - 10.3 lbs, Control - 7.5 lbs (p=0.09)
• Findings: In this randomized clinical trial, early time-restricted eating was more effective for losing weight and improving diastolic blood pressure and mood than eating over a window of 12 or more hours at 14 weeks.

• RCT
  Intermittent Fasting vs Usual Eating for Weight Loss in Overweight Individuals, JAMA Intern Med (2020) [PubMed abstract]
• Design: Randomized controlled trial (N=116 | length = 12 weeks) in adults with a BMI of 27 - 43
• Treatment: Intermittent fasting (no calories from 8PM to 12PM the following day) vs Usual eating. No recommendations on calorie intake or physical activity were given.
• Primary outcome: Weight loss at 12 weeks
• Results:
• Primary outcome (weight loss): Intermittent fasting - 2 lbs (0.94 kg), Usual eating - 1.5 lbs (0.68 kg) (p=0.63)
• Findings: Time-restricted eating, in the absence of other interventions, is not more effective in weight loss than eating throughout the day

• RCT
  Intermittent Fasting vs Usual Eating for Weight Loss in Adults with Obesity and Prediabetes or Diet-controlled Diabetes, Ann Intern Med (2024) [PubMed abstract]
• Design: Randomized controlled trial (N=41 | length = 12 weeks) in obese adults (average BMI 36) with prediabetes or diet-controlled diabetes
• Treatment: Intermittent fasting (10-hour eating window, 80% of calories before 1 p.m.) vs Usual eating (≤ 16-hour window, ≥ 50% of calories after 5 p.m.). Subjects received isocaloric diets with equivalent micro- and macronutrient composition; calorie amounts were based on metabolic needs and activity levels. Food was prepared in a study kitchen and consumed onsite or taken home.
• Primary outcome: Change in body weight at 12 weeks
• Results:
• Baseline weight: Intermittent fasting - 210 lbs (95.6 kg), Usual eating - 228 lbs (103.7 kg)
• Primary outcome (weight loss): Intermittent fasting - 5.1 lbs (2.3 kg), Usual eating - 5.7 lbs (2.6 kg) (diff 0.3 kg, 95%CI [-1.2 to 1.9 kg])
• Findings: In the setting of isocaloric eating, intermittent fasting did not decrease weight or improve glucose homeostasis relative to usual eating, suggesting that any effects of intermittent fasting on weight in prior studies may be due to reductions in caloric intake.

• RCT
  Intermittent Fasting vs Calorie Restriction vs Usual Eating, Ann Intern Med (2023) [PubMed abstract]
• Design: Randomized controlled trial (N=90 | length = 12 months) in racially-diverse obese adults
• Treatment: Intermittent fasting (eating between noon and 8 PM) vs Calorie-restricted diet (25% energy restriction daily) vs Usual eating (control)
• Primary outcome: Change in body weight, metabolic markers, and energy intake by month 12
• Results:
• Percent weight reduction (difference from control): Intermittent fasting - 4.87%, Calorie restriction - 5.3%
• Mean calorie reduction: Intermittent fasting - 425 kcal/d, Calorie restriction - 405 kcal/d
• Both interventions were significantly better than control. There was no significant difference between intermittent fasting and calorie restriction.
• Findings: Time-restricted eating is more effective in producing weight loss when compared with control but not more effective than calorie restriction in a racially diverse population.

• Summary
• Intermittent fasting did not enhance weight loss in four studies and had a modest effect in another. Long-term adherence to the time constraints seems impractical, making it a fad diet for most.

• Overview
• See weight loss drugs below for a list of FDA-approved therapies. Plenity®, an oral capsule, is also available, but the FDA considers it an "ingested, transient, space-occupying device."
• Weight loss procedures are reviewed here - weight loss procedures
• The table below ranks medications and procedures by their effectiveness

• PDF version of table

• Weight loss medication classes
• Appetite suppressants
• Benzphetamine (Didrex®)
• Diethylpropion HCL (Tenuate®)
• Phendimetrazine (Bontril® PDM)
• Phentermine HCL (Adipex-P®)


• Contrave® (bupropion + naltrexone)


• GLP-1 drugs
• Zepbound® (tirzepatide)
• Saxenda® (liraglutide)
• Wegovy® (semaglutide)


• Lipase inhibitors (orlistat)
• Xenical®
• Alli®


• Qsymia® (topiramate + phentermine)

• NOTE: the Plenity manufacturer, Gelesis, filed for bankruptcy in October 2023, and it is unclear if Plenity is still available.

• Mechanism of action
• Plenity capsules contain particles of a nonsystemic superabsorbent hydrogel composed of cellulose and citric acid. After ingestion, the particles are released in the stomach, where they absorb 100 times their original weight, forming a gel that occupies a quarter of the space. During a meal, the gel mixes with ingested food to increase its volume, enhancing fullness and satiety. The gel then passes through the small intestine and into the colon, where it is degraded before being eliminated in the stool. See YouTube video on how Plenity works.
• Despite its capsule form, Plenity is considered a medical device by the FDA, which describes it as an "ingested, transient, space occupying device for weight management and/or weight loss."

• FDA-approved indication
• Plenity is approved as an aid in weight management in overweight and obese adults, with a BMI of 25 - 40 kg/m², when used in conjunction with diet and exercise

• Side effects
• Plenity side effects include diarrhea (13%), abdominal distension (12%), infrequent bowel movements (9%), flatus (9%), and abdominal pain (5%). See GLOW study below.

• Contraindications / Precautions
• Pregnancy - DO NOT USE
• History of allergy to cellulose, citric acid, sodium stearyl fumarate, gelatin, or titanium dioxide - DO NOT USE
• Esophageal anatomic anomalies, including webs, diverticuli, and rings - DO NOT USE
• Suspected strictures (such as patients with Crohn's disease) - DO NOT USE
• Complications from prior gastrointestinal (GI) surgery that could affect GI transit and motility - DO NOT USE
• Gastro-esophageal reflux disease (GERD), ulcers, or heartburn - use caution. May worsen symptoms.

• Drug interactions
• Plenity is not absorbed so it does not have systemic drug interactions, but the gel it forms could theoretically affect drug absorption. A study evaluating its effects on metformin absorption found that while absorption was decreased, the effect was no different than that of food.
• The Plenity prescribing information offers no real guidance on administering concomitant medications. Based on the metformin study, it can be assumed that Plenity has a similar effect as food, although this has not been studied extensively.
• In general, patients should try to take their medications 1 hour before or 4 hours after Plenity when possible

• Dosage form
• Plenity comes in a pod that contains 3 capsules. Fourteen pods equal a week's worth of treatment.
• Plenity is only available from a mail-order pharmacy called GoGoMeds. A four-week supply costs $98.
• NOTE: the Plenity manufacturer, Gelesis, filed for bankruptcy in October 2023, and it is unclear if Plenity is still available.

• Dosing
• Dosing: 3 capsules (1 pod) 20 - 30 minutes before lunch and dinner. For each dose, patients should follow these steps:
• 1. Swallow 3 capsules with water
• 2. After taking the capsules, drink 2 additional glasses of water (8 fl oz/250 ml each)
• 3. Wait 20 - 30 minutes to begin to eat
• If a dose is missed, Plenity can be taken during or immediately after a meal

• Summary
• Plenity is a new "medical device" that may help some people lose weight by increasing food satiety. Based on the results of the GLOW study, a person who weighs 218 pounds can expect to lose an additional 4.4 pounds over 24 weeks if they add Plenity to diet and exercise.

• Carbohydrates
• Fatty acids
• Protein

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• 37 - SSED for dual intragastric balloon
• 38 - PMID 16476868 - AIM MA on low-carb vs low-fat
• 39 - AspireAssist SSED on FDA website
• 40 - PMID 33832655 AGA Clinical Practice Guidelines on Intragastric Balloons in the Management of Obesity, Gastroenterology (2021)