How Low Carb Diets Work
Low carb diets restrict carb intake to as little as 20 grams per day, such as the case in the Ketogenic diet. This restriction prompts a metabolic process known as ketosis, where the body begins to burn body fat and dietary fat for fuel instead of dietary carbs, which turn into glucose fuel in the body.
Contrary to all the hype about fat, low carb diets are fat rich and are primarily focused on a high intake of healthy fats, which in turn promote the body’s natural fat burning process.
But what about cholesterol?
What The Studies Show
The Mayo Clinic states that a ketogenic diet has desirable effects on diabetes, heart disease, and metabolic syndrome and that eating a low carb diet is more effective in lowering bad HDL cholesterol than diets that are moderate in carbs.
While some studies have shown the intake of saturated fat to raise blood cholesterol levels, these studies are almost always short in duration, as little as a few weeks. In fact, several long-term studies have shown no association between saturated fat and high blood cholesterol levels.
Additionally, studies of low-carbohydrate high saturated fat diets suggest no impact on blood cholesterol and in fact lower markers for heart disease.
One study (Barclay AW, Petocz P, McMillan-Price J, et al. Glycemic index, glycemic load, and chronic disease risk–a meta-analysis of observational studies) concluded that using the glycemic index (GI scale that rates a food’s ability to impact blood glucose levels) to consume lower GI foods is associated with lower triglycerides and higher good HDL cholesterol profiles.
The first ever conducted Bayesian study (a summary approach to mass data that makes it easier for doctors to understand) of the effects of diet therapy on weight loss (Sackner-Bernstein, Kanter, Kaul) that was published in October of 2015 evaluated data from 17 randomized controlled trials of 1,797 people who were obese and overweight. The evaluation found greater weight loss and a reduced predictor of cardiovascular disease risk in subjects who ate low carb versus low fat. The studies leader, Dr. Sackner-Bernstein commented that the results showed a low carb diet to have a 99% probability of resulting in greater weight loss and a clear higher likelihood that it was superior to restricting fat.
One meta-analysis (Santos, et al; Systematic review and meta-analysis of clinical trials of the effects of low carbohydrate diets on cardiovascular risk factors) of 17 low carb diet trials comprised of 1,140 obese subjects determined that eating low carb neither increased nor decreased the bad LDL cholesterol.
Instead, low carb was associated with:
- Significant weight loss and reduced body mass index
- Significant improvements in several heart disease risk factors: lower level of triglycerides, healthier blood pressure
- Improved fasting glucose
- Reduced risk for metabolic syndrome, which is a risk factor for heart disease
- Decreased levels of belly fat and waist size
- Improvements in the good HDL cholesterol levels
Another study (Siri-Tarino, et al; Saturated Fatty Acids and Risk of Coronary Heart Disease) reported that the replacement of saturated fat with carbohydrates, and especially refined carbs and sugars that have become commonplace in the last several decades is associated with either no improvement in or increased risks for cardiovascular disease as well as higher risks for dyslipidemia.
The study’s researchers concluded that considering the current epidemic levels of obesity, and type 2 diabetes that features insulin resistance, reducing intake of carbs and sugar along with weight control should be a top priority in the public’s dietary goals.
Other Key Considerations
Moreover, no low carb diet advocates trans fats (also known as partially hydrogenated vegetable oil or hydrogenated vegetable oil) which are the worst fats contributing to an increased risk for heart disease.
Trans fats are typically found in fried foods, sweets, baked goods, processed snacks and food products, cookies, crackers and vegetable shortenings, none of which is allowed on any reputable low carb plan.
You should talk with your doctor before altering your diet, especially if you suffer from heart disease or high cholesterol. A nutritionist or a dietician can help as well.