AN OBESITY & DIABETES EPIDEMIC
It doesn’t take a lot of health research to conclude that the United States is in a health crisis and that that crisis is getting more severe. Some of the most glaring and shocking statistics center around topics like obesity and diabetes.
With obesity, we all know that America has an ever expanding problem with its ever expanding collective waist line. As of 2018 (the most recent year for which accurate data on obesity is available), roughly 43% of Americans were obese (BMI >30) and if you throw in those in the overweight category (BMI 25-29.9) that number jumps to nearly 75%. While BMI (body mass index) is by no means a perfect indicator of a healthy body composition (ex. adults with big frames and high muscle mass are often miscategorized as overweight), it’s still useful when assessing body composition trends in a large population. For instance, in 1960 only 10% of Americans were considered obese by their BMI number.
And just how overweight are we as a society? Well, the average American adult man is approximately 35lbs overweight (200lbs for the average 5’9” man) and the average American woman is around 40-45lbs overweight (170lbs for the average 5’4” woman). 
With diabetes, the numbers are just as bad. As of 2019, more than 37 million Americans (>11%) had diabetes and approximately 96 million adults were prediabetic (that’s more than 1 in 3 American adults). In 1960 less than 1% of Americans were diabetic. [2-3]
Why are these numbers such a big deal? In part because of the mortality risk associated with obesity and diabetes. A 2022 study in the Lancet found that excess weight was responsible for more than 500,000 deaths per year in the United States and a 2022 study in the BMJ highlighted the fact that diabetes had killed more than 100,000 Americans in each of the previous 2 years (2020-21). [4-5]
And this isn’t to mention the effects obesity, excess weight and diabetes have on quality of life, or how they dramatically increase the likelihood of developing other common serious conditions (ex. heart disease, cancer, arthritis, infectious diseases, etc.). 
EXCESS CARBS AS A PRIMARY DRIVER OF OBESITY & DIABETES
Several factors drive conditions like obesity and diabetes (ex. genetics, lack of exercise and physical activity, poor sleep, stress, the effects of certain medications, etc.), perhaps no factor impacts obesity and diabetes as much as nutritional intake, and more specifically, carbohydrate intake.
Of course this is a controversial statement, as the traditional paradigm around macronutrient intake and obesity (and to a degree, diabetes) was one built on the energy balance model (EBM), which tries to reduce each macronutrient (mainly proteins, fats and carbs) down to a unit of energy (calorie or Kcal). And because fats are assigned 9 calories to the 4 calories assigned to proteins and carbohydrates, an almost incomprehensible amount of scientific effort went into the task of linking a high fat diet to diseases like obesity, diabetes and heart disease (this is the Lipid Hypothesis). Unfortunately for those espousing the energy balance model (the “calories in, calories out” and “energy balance” crowd), the actual evidence seems to lend more support to another model- the carbohydrate insulin model (CIM) of obesity, which highlights the unique physiological effects each macronutrient has when consumed, in particular the effect each macronutrient has on blood sugar and insulin levels.
While there’s conflicting scientific data on this topic (as there generally is with any contested topic in health), an increasing amount of research points to the CIM as being a more accurate framework with which to understand obesity and diabetes. Put more simply- it’s excess carb intake that’s primarily driving diseases like obesity and diabetes, not dietary fat (or protein). Of course if excess carbs are a primary cause, then low carb diets (including keto and Atkins) are often a big part of the solution (the keto diet generally keeps net carbs between 20-50g/day).
THE SCIENCE AROUND OBESITY, DIABETES,
CARBS AND DIETS LIKE KETO
For instance, the authors of a 2017 study concluded that…
“A ketogenic diet has beneficial effects on cardiac ischemic preconditioning, improves oxygenation in patients with respiratory failure, improves glycemic control in diabetics, is associated with significant weight loss, and has a beneficial impact on polycystic ovarian syndrome… A ketogenic diet is currently regarded as apt dietary therapy for ‘diabesity’ (diabetes with obesity).” 
A 2018 study in JAMA highlighted that “studies tend to show metabolic advantages for low-glycemic load vs low-fat diets.” 
The authors of another 2018 study state that “ketogenic diets promote breakdown of excess fat stores, sparing of lean muscle, and improvement in insulin sensitivity… compelling evidence exists for the use of nutritional ketosis for the management of weight and the components of metabolic syndrome.” 
Yet another 2018 study also highlighted many of the positive effects of a low carb diet. The authors state…
“The majority of… studies demonstrate that individuals who follow a low-carbohydrate diet lose more weight during the first 3-6 months compared with those who follow more balanced diets… Besides a positive effect on weight loss, studies have shown that low-carbohydrate ketogenic diets also reduce serum triglycerides dramatically… (and) low-carbohydrate ketogenic diets have been shown to have immense benefits in blood sugar control. There are some reported beneficial effects on cancer and neurological disorders such as Alzheimer's disease and epilepsy.” 
A 2019 study in the journal Nutrients found that “Reducing carbohydrate intake with a low carb diet is effective in reducing body weight and, in patients with type 2 diabetes, improving glycemic control, with a stronger effect with a very low carb diet (ketogenic diet).” 
The authors of a 2020 study had this to say about a low carb diet compared to a low fat diet…
“(Keto and low carb diets” have a long history in clinical medicine. Ketogenic diets appear to be more effective than low-fat diets for treatment of obesity and diabetes. In addition to the reductions in blood glucose and insulin achievable through carbohydrate restriction, chronic ketosis might confer unique metabolic benefits of relevance to cancer, neurodegenerative conditions, and other diseases associated with insulin resistance. Based on available evidence, a well-formulated ketogenic diet does not appear to have major safety concerns for the general public and can be considered a first-line approach for obesity and diabetes.” 
Another 2020 study tested a low carb diet (<10% calories from carbs) versus a low fat diet (<20% of calories from fats) with 34 men and women aged 60-75 with obesity. After 8 weeks, the low carb diet participants lost an average of 9.7% of total body fat (i.e. nearly 25lbs for a 250lbs person) while the low fat diet participants lost just 2.0% of total body fat (i.e. about 5lbs for a 250lbs person). 
A 2023 report (StatPearls) on the Keto Diet states that “The resurgence of the ketogenic diet as a rapid weight loss formula is a relatively new concept that has shown to be quite effective, at least in the short run.” 
Lastly, a 2023 RCT of 609 obese and overweight participants (ages 18-50 years) were assigned to either a 12 month low carb diet or low fat diet. The authors found that…
“Measures related to carbohydrate intake (total amount, glycemic index, added sugar) showed strong associations with weight loss at 3, 6 and 12-mo time points… whereas those related to total fat intake showed weak to no associations. Glycemic load explained most of the observed effect of total calorie intake on weight change. As predicted by the carbohydrate-insulin model of obesity, weight loss in both diet groups… seems to have been driven by the reduction of glycemic load more so than dietary fat or calories.” 
200 YEARS OF THE LOW CARB DIET
Restricting carbohydrates to promote healthy weight loss is hardly new. In the 1820s, French lawyer, politician and food writer Jean Brillat-Savarin promoted a diet void of starches and most carbohydrates. Four decades later, William Banting, a prominent undertaker, went on to promote a low carb diet after personally using it to lose a significant amount of weight. In the 1920s, Dr. Russell Wilder MD of the Mayo Clinic developed the keto diet- a low carb, high fat diet that was originally geared toward healing those with epilepsy. In the 1960s, cardiologist Dr. Robert Atkins famously developed his Atkins diet, borrowing many of the same principles of earlier low carb adherents and researchers. Today, prominent figures like Dr. Jason Fung MD, Dr. Stephen Gundry MD, Dr. Mark Hyman MD and Dr. David Perlmutter MD all regularly promote a version of the low carb diet to combat several common conditions, including obesity and diabetes. 
PROGRAMMING LOW CARB FOR
WEIGHT LOSS, DIABETES, GUT HEALTH & INFLAMMATION
I regularly program personalized low carb diets for my clients dealing with excess weight, diabetes and digestive issues (ex. gut dysbiosis, leaky gut/intestinal hyperpermeability). Regarding the gut microbiome, higher carb intake tends to exacerbate an imbalanced gut flora in part by “feeding” pathogenic bacteria and yeast. Most of the clinical data shows low carb and keto diets have positive effects on the gut microbiome. [17-21]
Because the gut microbiome so strongly impacts the immune and neurological systems, improvements in gut health also commonly improve chronic issues in these areas as well.
Sometimes my programming for this population is a keto diet (where net carbs are limited to <50g/day) but more often it’s a quasi-keto diet with a slightly higher carbohydrate intake, but one still low enough to promote accelerated body fat loss, significant reductions in elevated blood sugar and insulin levels, and notable improvements in digestive functioning.
Lastly, because chronically high blood sugar levels due to excessive carbohydrate consumption tend to drive glycation (a process that drives inflammation and soft tissue breakdown in large part through the creation of Advanced Glycation End products), reducing chronically elevated blood sugar levels also tends to drive down inflammation, resulting in less joint pain and improvements in inflammatory biomarkers like CRP, ESR and homocysteine. [22-25]
1 www.niddk.nih.gov/health-information/health-statistics/overweight-obesity (statistics on obesity)
2 www.cdc.gov/diabetes/library/spotlights/diabetes-facts-stats.html (stats on diabetes)
3 www.cdc.gov/diabetes/basics/prediabetes.html (stats on prediabetes)
4 www.thelancet.com/journals/eclinm/article/PIIS2589-53702200159-6/fulltext (2022 study on obesity and mortality)
5 www.bmj.com/content/376/bmj.o300 (2022 study on diabetes and mortality)
6 www.ncbi.nlm.nih.gov/pmc/articles/PMC4859313/ (2015; epidemiology of obesity)
7 www.ncbi.nlm.nih.gov/pmc/articles/PMC5664869/ (2017 study on numerous benefits associated with a ketogenic diet)
8 www.ncbi.nlm.nih.gov/pmc/articles/PMC6082688/ (2018; carbohydrate insulin model of obesity; “studies tend to show metabolic advantages for low-glycemic load vs low-fat diets.”)
9 www.ncbi.nlm.nih.gov/pmc/articles/PMC6472268/ (2018 study on ketogenic diets, body composition and metabolic markers)
10 www.ncbi.nlm.nih.gov/pmc/articles/PMC6251269/ (2018 study on numerous benefits of low carbohydrate diets)
11 www.ncbi.nlm.nih.gov/pmc/articles/PMC6566854/ (2019 study on low carb & keto diets in type 1 & 2 diabetes)
12 www.ncbi.nlm.nih.gov/pmc/articles/PMC7269727/ (2020 on benefits of smart keto diet)
13 www.ncbi.nlm.nih.gov/pmc/articles/PMC7425171/ (2020 study of 34 obese participants assigned to either low carb or low fat diet group)
14 www.ncbi.nlm.nih.gov/books/NBK499830/ (2023 stat pearls on Keto Diet)
15 https://pubmed.ncbi.nlm.nih.gov/36811468/ (2023 study of 609 participants with overweight or obesity (aged 18-50y) were assigned to a 12-mo LCD or LFD)
17 www.ncbi.nlm.nih.gov/pmc/articles/PMC8747023/ (2022; “Multiple studies have shown the beneficial effects of a ketogenic diet on metabolic health and reduced seizure activities. These effects are likely, at least in part, mediated via the gut microbiota.”)
18 www.ncbi.nlm.nih.gov/pmc/articles/PMC9110973/ (2022; “Low carb diet intervention did not change the diversity and overall structure of gut microbiota. Combining low carb diet with exercise training may have additional benefits on gut physiology. Specific microbial genera were associated with low carb diet and exercise-induced regulation of cardiometabolic health.”)
19 www.ncbi.nlm.nih.gov/pmc/articles/PMC7293577/ (2021; “Keto diet associated gut microbiota reduces the levels of intestinal pro-inflammatory Th17 cells.”)
20 www.ncbi.nlm.nih.gov/pmc/articles/PMC6678592/ (2019; “A few human and animal studies have shown different results demonstrating positive effects on reshaping bacterial architecture and gut biological functions, while others reporting negative effects as a lowered diversity and an increased amount of pro-inflammatory bacteria.”)
21 www.nature.com/articles/s41598-018-25190-5 (2018; “Keto diet also increased the relative abundance of putatively beneficial gut microbiota (Akkermansia muciniphila and Lactobacillus) and reduced that of putatively pro-inflammatory taxa (Desulfovibrio and Turicibacter).”)
22 https://pubmed.ncbi.nlm.nih.gov/32246887/ (2021 study on AGEs)
23 www.ncbi.nlm.nih.gov/pmc/articles/PMC7188081/ (2020 study on AGEs)
24 www.ncbi.nlm.nih.gov/pmc/articles/PMC6147582/ (2018 study on AGEs)
25 www.ncbi.nlm.nih.gov/pmc/articles/PMC5409724/ (2017 study on the negative physical effects of AGEs, produced endogenously via high blood sugar, oxidative stress and glycation, and exogenously from pollution, smoke, high heat treated and ultra processed foods)