By: Dr. Mary Pardee
The Growing Epidemic: Understanding and Addressing Obesity
Obesity has become a significant global health crisis, and its prevalence is on the rise.
Recent data shows an alarming increase in obesity rates over the past decades.
According to the National Health and Nutrition Examination Survey (NHANES), obesity rates in the United States have escalated dramatically: from 22.9% in 1988-1994, to 41.9% in 2017-2020 (1).
Globally, approximately 604 million adults were classified as obese in 2015, with higher rates observed among females across all socioeconomic levels and age groups (2).
From 1990 to 2022, the age-standardized prevalence of obesity rose in 90% of countries, with particularly notable increases among females in 25% of countries and males in 12% of countries (3).
Risks of Obesity
Obesity is more than just a number on a scale; it poses serious health risks. Individuals with higher body mass indexes (BMIs) face a significantly increased likelihood of developing health conditions such as:
Type 2 diabetes
Hypertension (high blood pressure)
Dyslipidemia (cholesterol)
Coronary heart disease
The higher the BMI, the greater the risk of both morbidity (the presence of health conditions) and mortality (the likelihood of death) (4).
Waist Circumference: A Better Indicator?
BMI is not a perfect measure. It calculates weight relative to height but does not distinguish between fat and muscle. Therefore, it may overestimate body fat in highly muscular individuals, like athletes, and underestimate it in older adults who have lost muscle mass.
For a more accurate assessment of health risks related to obesity, waist circumference is a valuable tool.
Abdominal obesity, or visceral fat, is linked to increased risks of:
Heart disease
Diabetes
Hypertension
Metabolic disorders (5).
Measuring waist circumference involves placing a tape measure around the abdomen at the top of the hip bone while standing (see image below).
A waist circumference of ≥40 inches (102 cm) for men and ≥35 inches (88 cm) for women is considered elevated and indicative of increased cardiometabolic risk (4).
Image Source: UpToDate “Obesity in Adults: Overview of Management”
Causes of Weight Gain and Obesity
Weight gain occurs when the energy intake (calories consumed) exceeds energy expenditure (calories burned). Several factors contribute to this imbalance:
Diet: Research shows that certain foods are associated with weight gain, such as potato chips, French fries, and sugary desserts, while others, like yogurt, fruits, and vegetables, may help prevent weight gain (6). The consumption of ultraprocessed foods, such as pizza and soda, has also been linked to obesity. Studies have demonstrated that diets high in ultraprocessed foods increase caloric intake and weight, while diets focusing on whole foods tend to support weight management (7,8).
Physical Activity: In the past, many jobs required moderate physical activity, but today, over 70% of workers are sedentary or engaged in light physical work. Sedentary behaviors, especially prolonged TV watching, are strongly associated with obesity and diabetes. For example, every two-hour increment of TV watching increases the risk of obesity by 23% (9). See table below to see how activity levels decline with age.
Genetics: Studies estimate that genetics account for 40-70% of obesity risk. Individuals with one obese parent have a 3-4 times higher risk of obesity, and those with two obese parents face over a 10-fold increased risk (10, 11).
Medications and Other Factors: Certain medications, including insulin, oral contraceptives, glucocorticoids, and some antidepressants, can lead to weight gain.
Microbiome: The gut microbiome also plays a role, with some studies linking specific gut bacteria compositions to obesity. There have been a large number of studies demonstrating an association between the proportion of Bacteroidetes and Firmicutes bacteria in the gut and the development of obesity. It is less clear, however, that the relationship is causal (12).
Endocrine-disrupting chemicals: Endocrine-disrupting chemicals are compounds that are used in the production of a wide range of commercial products. They have been found in environmental water samples and the food supply and can accumulate in human tissues. A growing number of studies have linked exposure to these compounds to both childhood and adult obesity. Based on observational studies, bisphenol A (plastics) and perfluorinated chemicals (water, non-stick cookware, food packaging, etc) may be the most strongly associated (13).
Menopause: For women, menopause often leads to weight gain, specifically decreased lean muscle mass and increased abdominal fat. This is due to reduced estrogen levels and decreased energy expenditure (14).
Menopausal hormone therapy (MHT) has been shown to mitigate some of these changes by reducing visceral adipose tissue accumulation and preserving lean body mass. However, estrogen therapy does not prevent weight gain in postmenopausal females, although it may minimize fat redistribution. In a three-year trial including over 800 participants from the Women's Health Initiative (WHI), those who received estrogen and progesterone therapy lost less lean muscle mass and had less change in fat distribution compared with those receiving placebo (15).
Evaluating Weight and Health
To effectively manage obesity, it's essential to evaluate various factors, including thyroid function, blood sugar levels, inflammatory markers, and sex hormones. Tools like the DEXA scan can assess lean muscle mass and fat distribution.
Effective Weight Loss Strategies
Lifestyle Changes: Successful weight loss involves a combination of diet, exercise, and behavioral modifications. Key dietary strategies include reducing caloric intake, eliminating sugary and processed foods, and focusing on whole, nutrient-dense foods. Self-monitoring, such as using food diaries and activity records, can enhance weight loss efforts.
Intermittent Fasting: While intermittent fasting (restricting eating to a specific window of time) can support weight loss, studies do not show that intermittent fasting causes weight loss independent of caloric restriction (16, 17). The benefit of intermittent fasting is likely due to the fact that having a smaller eating window leads to less calories consumed.
Exercise: Regular physical activity, including both aerobic and resistance training exercises, is crucial for weight management. Aiming for at least 30 minutes of exercise most days of the week helps prevent weight gain and supports cardiovascular health.
Medications: For some individuals, medications such as tirzepatide and semaglutide can aid in weight loss by mimicking hormones that regulate appetite and insulin.
Protein-rich breakfast: This helps with appetite and satiety throughout the rest of the day, which can lead to fewer calories consumed. A meta-analysis by Qiu showed that protein-rich breakfasts in children and adolescents resulted in lower subsequent energy intake and increased feelings of fullness compared to normal protein breakfasts (18).
Caffeine: A systematic review and meta-analysis of randomized controlled trials (RCTs) demonstrated that caffeine intake is associated with reductions in weight, body mass index (BMI), and fat mass. Caffeine can promote weight loss by increasing energy expenditure, enhancing fat breakdown, and suppressing appetite, leading to reductions in weight, BMI, and fat mass (19).
Debunking Myths
Cortisol and Weight Loss: Normal increases in cortisol levels are not harmful; they naturally increase in the morning and after exercise - this is NORMAL. Chronically elevated cortisol, as seen in conditions like Cushing’s syndrome, can contribute to weight gain, but this is an extreme case.
Food Quality vs. Quantity: While food quality is important, caloric intake is the primary factor in weight management. Excessive consumption of any food, regardless of quality, can lead to weight gain. At modrn med we advocate for a diet high in fruits and vegetables and low in ultra-processed hyperpalitable foods, especially for those trying to lose weight. However, the idea that “calories don’t matter” is… WRONG.
Carbohydrates: Carbohydrates alone do not cause weight gain. It’s the overall caloric intake. Whole grains, starches and fruits are beneficial (20). If calories in are less than calories out, even on a higher carbohydrate diet, a person will lose weight.
Fat-Burning Foods: Although foods like cinnamon have health benefits, they are not effective at reducing fat on their own. A balanced diet and lifestyle changes are more impactful for weight management.
Conclusion
Addressing obesity requires a comprehensive approach that considers dietary habits, physical activity, genetic factors, and other contributing elements. By understanding these factors and debunking common myths, individuals can better navigate their weight loss journey and improve their overall health.
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Citations:
Hales, Craig M et al. “Prevalence of Obesity and Severe Obesity Among Adults: United States, 2017-2018.” NCHS data brief ,360 (2020): 1-8.
GBD 2015 Obesity Collaborators et al. “Health Effects of Overweight and Obesity in 195 Countries over 25 Years.” The New England journal of medicine vol. 377,1 (2017): 13-27. doi:10.1056/NEJMoa1614362
NCD Risk Factor Collaboration (NCD-RisC). “Worldwide trends in underweight and obesity from 1990 to 2022: a pooled analysis of 3663 population-representative studies with 222 million children, adolescents, and adults.” Lancet (London, England) vol. 403,10431 (2024): 1027-1050. doi:10.1016/S0140-6736(23)02750-2
Jensen, Michael D et al. “2013 AHA/ACC/TOS guideline for the management of overweight and obesity in adults: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and The Obesity Society.” Circulation vol. 129,25 Suppl 2 (2014): S102-38. doi:10.1161/01.cir.0000437739.71477.ee
Koster, Annemarie et al. “Waist circumference and mortality.” American journal of epidemiology vol. 167,12 (2008): 1465-75. doi:10.1093/aje/kwn079
Mozaffarian, Dariush et al. “Changes in diet and lifestyle and long-term weight gain in women and men.” The New England journal of medicine vol. 364,25 (2011): 2392-404. doi:10.1056/NEJMoa1014296
Rauber, Fernanda et al. “Ultra-processed food consumption and indicators of obesity in the United Kingdom population (2008-2016).” PloS one vol. 15,5 e0232676. 1 May. 2020, doi:10.1371/journal.pone.0232676
Hall, Kevin D et al. “Ultra-Processed Diets Cause Excess Calorie Intake and Weight Gain: An Inpatient Randomized Controlled Trial of Ad Libitum Food Intake.” Cell metabolism vol. 30,1 (2019): 67-77.e3. doi:10.1016/j.cmet.2019.05.008
Hu, Frank B et al. “Television watching and other sedentary behaviors in relation to risk of obesity and type 2 diabetes mellitus in women.” JAMA vol. 289,14 (2003): 1785-91. doi:10.1001/jama.289.14.1785
Frayling, Timothy M et al. “A common variant in the FTO gene is associated with body mass index and predisposes to childhood and adult obesity.” Science (New York, N.Y.) vol. 316,5826 (2007): 889-94. doi:10.1126/science.1141634
Whitaker, Katriina L et al. “Comparing maternal and paternal intergenerational transmission of obesity risk in a large population-based sample.” The American journal of clinical nutrition vol. 91,6 (2010): 1560-7. doi:10.3945/ajcn.2009.28838
Maruvada, Padma et al. “The Human Microbiome and Obesity: Moving beyond Associations.” Cell host & microbe vol. 22,5 (2017): 589-599. doi:10.1016/j.chom.2017.10.005
Kahn, Linda G et al. “Endocrine-disrupting chemicals: implications for human health.” The lancet. Diabetes & endocrinology vol. 8,8 (2020): 703-718. doi:10.1016/S2213-8587(20)30129-7
Van Pelt, Rachael E et al. “Regulation of Body Composition and Bioenergetics by Estrogens.” Endocrinology and metabolism clinics of North America vol. 44,3 (2015): 663-76. doi:10.1016/j.ecl.2015.05.011
Chen, Zhao et al. “Postmenopausal hormone therapy and body composition--a substudy of the estrogen plus progestin trial of the Women's Health Initiative.” The American journal of clinical nutrition vol. 82,3 (2005): 651-6. doi:10.1093/ajcn.82.3.651
Maruthur, Nisa M et al. “Effect of Isocaloric, Time-Restricted Eating on Body Weight in Adults With Obesity : A Randomized Controlled Trial.” Annals of internal medicine vol. 177,5 (2024): 549-558. doi:10.7326/M23-3132
Liu, Deying et al. “Calorie Restriction with or without Time-Restricted Eating in Weight Loss.” The New England journal of medicine vol. 386,16 (2022): 1495-1504. doi:10.1056/NEJMoa2114833
Qiu, Meijuan et al. “Effect of Protein-Rich Breakfast on Subsequent Energy Intake and Subjective Appetite in Children and Adolescents: Systematic Review and Meta-Analysis of Randomized Controlled Trials.” Nutrients vol. 13,8 2840. 18 Aug. 2021, doi:10.3390/nu13082840
Tabrizi, Reza et al. “The effects of caffeine intake on weight loss: a systematic review and dos-response meta-analysis of randomized controlled trials.” Critical reviews in food science and nutrition vol. 59,16 (2019): 2688-2696. doi:10.1080/10408398.2018.1507996
Wan Y, Tobias D K, Dennis K K, Guasch-Ferré M, Sun Q, Rimm E B et al. Association between changes in carbohydrate intake and long term weight changes: prospective cohort study BMJ 2023; 382 :e073939 doi:10.1136/bmj-2022-073939
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