We’ve all been there: A search for sound nutritional advice starts with the best intentions but quickly veers down a rabbit hole. With ever-changing recommendations on what to eat and how much, making good food choices often feels like a guessing game.
Not all dietary guidance is created equal. Public health organizations like the U.S. Department of Agriculture, Food and Drug Administration, and National Institutes of Health base recommendations on clinical trials, epidemiological studies, and lab research on the body, its cells, and pathological changes.
As newer findings about food and nutrition emerge—some in stark contrast to previously accepted knowledge—so do modifications to dietary guidelines. More than 45 years of fluctuating instructions on fat and sugar show us how often and radically information can change.
Diet and Disease
The United States first rang the nutritional warning bell in the late 1970s when a senate committee published Dietary Goals. The report linked “too much” sugar, fat, saturated fat, and cholesterol to chronic disease, stirring controversy among the medical and nutrition communities. How the food industry responded fundamentally changed the American diet. Production of low-fat foods skyrocketed as those heeding the government’s advice sought substitutes for household favorites. What these products lacked in calories and fat, they made up for with carbohydrates. Subsequently, U.S. obesity rates began to climb.1Willett, Walter, MD. “Did the Low-Fat Era Make Us Fat?” Frontline. Published April 8, 2004. Accessed September 20, 2023. https://www.pbs.org/wgbh/pages/frontline/shows/diet/themes/lowfat.html#:~:text=With%20more%20fat%2Dfree%20products,during%20this%20period%20of%20time
Cholesterol’s insidious effect on coronary arteries, which supply blood to the heart muscle, struck fear in the hearts of the public. High cholesterol levels were swiftly linked to coronary artery disease and heart attacks, prompting discouragement of dairy, red meat, and other saturated fats.1Willett, Walter, MD. “Did the Low-Fat Era Make Us Fat?” Frontline. Published April 8, 2004. Accessed September 20, 2023. https://www.pbs.org/wgbh/pages/frontline/shows/diet/themes/lowfat.html#:~:text=With%20more%20fat%2Dfree%20products,during%20this%20period%20of%20time
Carbs, Sugar, and Insulin
Despite Americans increasingly opting for low-fat and no-fat foods, obesity rates surged along with the prevalence of type 2 diabetes. Surprisingly, rates of heart disease remained relatively stable.
Sugar’s role in heart disease explains why low-fat diets didn’t produce expected outcomes. Carbohydrates are a good source of energy. When simple carbohydrates—glucose, fructose, and galactose—combine into a larger molecule, they form sucrose (table sugar), maltose, and lactose. Simple carbohydrates rapidly become glucose, the molecule our bodies use most efficiently for energy. Complex carbohydrates (starches and fiber) are sugar molecules strung together in long, complex chains. Although fiber aids gastrointestinal function and supports overall health, our bodies can’t digest it. During digestion, starches break down, ultimately becoming glucose.
Our cells rely on glucose to make energy, but they can only handle a limited amount of glucose at once. Most require insulin, a hormone produced by the pancreas, to regulate glucose. Insulin rushes through the bloodstream, seeking out receptors to fulfill its role.
As glucose levels rise in the bloodstream, the pancreas releases more insulin to help cells absorb glucose for energy production. Cells accept and use the glucose efficiently, prompting receptors to speed up. Over time, however, these cells use fewer receptors to manage glucose. This adaptation is called insulin resistance, a protective mechanism that mitigates an influx of glucose.
Insulin allows the conversion of glucose into a fat called triglycerides. Insulin helps cells take in the new fat, targeting the area around the naval. Upper—or central—body obesity is a sign of insulin resistance, also known as prediabetes. High blood insulin levels are another sign. When an exhausted pancreas can no longer produce insulin, glucose lingers in the blood, wreaking havoc on kidneys, retinae, nerves, and blood vessels.
People often attribute extra belly fat, fatigue, sugar cravings, increased thirst, and frequent urination to the normal aging process. However, even before these symptoms manifest, glucose alters the proteins in our bodies, rendering them inactive or less effective.
Blood tests will begin to show high glucose levels and elevated levels of certain fats (lipids). Abnormal lipid levels are known as dyslipidemia. The link is evident in studies on sweet drink consumption, which supplies even more simple carbohydrates to a body already experiencing regulatory mayhem.2Haslam et al. Beverage consumption and longitudinal changes in lipoprotein concentrations and incident dyslipidemia in US adults: the Framingham Heart Study. J Am Heart Assoc. 2020;9(5):e014083. https://doi.org/10.1161/JAHA.119.014083,3Welsh JA, Sharma A, Abramson JL, Vaccarino V, Gillespie C, Vos MB. Caloric sweetener consumption and dyslipidemia among US adults. JAMA. 2010;303(15):1490-1497. https://doi.org/10.1001/jama.2010.449
How ‘Bad Cholesterol’ Affects Arteries
When the body’s regulatory mechanisms start to falter, it triggers a chain reaction of negative changes that affect other internal systems. For instance, excessive fat accumulation in the abdominal region is called visceral fat because it surrounds the viscera, or internal organs, in the abdominal cavity. Blood that travels through the viscera must pass through the liver, where fats combine with proteins. They form compounds called lipoproteins. High-density lipoproteins (HDL) have more protein and less fat, while low-density lipoproteins (LDL) have less protein and more fat.
LDLs are notorious for altering connective tissue and other components of blood vessels, particularly arteries.4DiNicolantonio JJ, Lucan SC, O’Keefe JH. The evidence for saturated fat and sugar related to coronary heart disease. Prog Cardiovasc Dis. 2016;58(5):464-472. https://doi.org/10.1016/j.pcad.2015.11.006 Arteries react to this invasion by building more arterial muscle. Fatty plaques develop, narrowing the arteries and forcing the heart to work harder circulating blood to the body. High glucose levels ultimately lead to dyslipidemia and arterial damage, which may lead to heart attack or heart failure.
Nerve damage from glucose also contributes to general vessel damage. Compromised blood flow in the retinae, kidneys, and brain raises the risk of blindness, chronic kidney disease, and stroke. Uncontrolled diabetes, stemming from what was once just insulin resistance, poses life-threatening problems.
Regulating Glucose and Insulin
Regular physical activity and a healthy diet can turn all of this around. Strength-building exercises replace fatty tissue with lean muscle, which is less likely to develop insulin resistance.5Bhupathiraju SN, Hu FB. Epidemiology of obesity and diabetes and their cardiovascular complications. Circ Res. 2016;118(11):1723-1735. https://doi.org/10.1161/CIRCRESAHA.115.306825
It’s helpful to read nutrition labels, but even more important to choose foods that don’t require labels, such as fresh produce. While this can be challenging in areas with limited access to large grocery stores or fresh food markets, the simple goal is to eat more whole foods and less simple carbohydrates and sugar.
Whole grains and complex carbohydrates help regulate the flow of glucose and insulin in the body, leading to healthier cells, balanced blood glucose levels, and steady lipid metabolism.
Footnotes
- 1Willett, Walter, MD. “Did the Low-Fat Era Make Us Fat?” Frontline. Published April 8, 2004. Accessed September 20, 2023. https://www.pbs.org/wgbh/pages/frontline/shows/diet/themes/lowfat.html#:~:text=With%20more%20fat%2Dfree%20products,during%20this%20period%20of%20time
- 2Haslam et al. Beverage consumption and longitudinal changes in lipoprotein concentrations and incident dyslipidemia in US adults: the Framingham Heart Study. J Am Heart Assoc. 2020;9(5):e014083. https://doi.org/10.1161/JAHA.119.014083
- 3Welsh JA, Sharma A, Abramson JL, Vaccarino V, Gillespie C, Vos MB. Caloric sweetener consumption and dyslipidemia among US adults. JAMA. 2010;303(15):1490-1497. https://doi.org/10.1001/jama.2010.449
- 4DiNicolantonio JJ, Lucan SC, O’Keefe JH. The evidence for saturated fat and sugar related to coronary heart disease. Prog Cardiovasc Dis. 2016;58(5):464-472. https://doi.org/10.1016/j.pcad.2015.11.006
- 5Bhupathiraju SN, Hu FB. Epidemiology of obesity and diabetes and their cardiovascular complications. Circ Res. 2016;118(11):1723-1735. https://doi.org/10.1161/CIRCRESAHA.115.306825
