In an attempt to lose weight, many people turn to low-carbohydrate diets. While such diets can result in great and rather rapid reductions in body weight, they can (in some cases) also decrease heart health.
Reduction in carbohydrate intake often results in an increase in the proportion of fat consumption. This can increase the number of triglycerides (fats) in the blood, which can contribute to plaques on arteries and build up around the heart. Fatty foods usually contain high levels of cholesterols. There are two kinds of cholesterol: High-density lipoprotein (HDL) and low-density lipoproteins (LDL). LDLs form plaques on arterial walls, which can build up and lead to atherosclerosis–which, in turn, increases your risk of heart attack and stroke. For this reason, LDLs are often referred to as bad cholesterol. HDLs on the other hand, are termed good cholesterol because they can remove fat molecules from arterial walls. Fatty foods can contain both of these kinds of cholesterols, in different ratios.
Despite this possible shortcoming, low carbohydrate, high-fat diets are a great method for losing weight, and reduction in fat stores is itself heart-healthy. Visceral fat–the fat in the abdomen that packs itself between organs–actually releases enzymatic signals that stimulate the release of very low-density lipoproteins from the liver. When released into the bloodstream, these VLDLs become LDLs. Just having more visceral fat can therefore lead to heart problems.
So how does one lose weight with a low-carb diet and remain heart-healthy? Here are some tips.
Some people who partake in low-carb diets, such as the Atkins diet, rely heavily on animal sources for protein. One study suggests that this kind of diet may lead to increased mortality (1.1 times that of the general population) (Fung et al., 2010). Low-carb dieters who consume more vegetables, on the other hand, showed reduced mortality (0.8 times the general population). A low-carb diet incorporating high amounts of vegetables and a lower amount of meat seems to increase heart health.
Abrupt transition to a low carb diet can be a shock to the body. There is fast depletion of fat stores, and trapped in this fat is lots of water. During the beginning of a low-carb diet, dieters can feel lethargic because of the loss of glycogen stores, and also become dehydrated. Dehydration can decrease blood volume, which makes it harder for the heard to pump blood. In individuals with pre-existing heart conditions, this can overtax the heart. People transitioning to a low-carb diet should drink more water than usual to compensate for this and stay hydrated.
Low carb diets can drastically restrict the types of foods one is allowed to consume. This can lead to nutritional deficits, including lowered calcium and potassium levels, among others (Freedman et al. 2001), that are essential for a working heart. Supplementing ones diet with vitamins will reduce the risk for nutrient deficiency, as will the active inclusion of nutrient-rich foods into your diet.
ExerciseSome low-carb dieters perceive the diet as healthy without exercise, a few going so far as to recommend against exercise. This likely stems from the fatigued feeling during the first few weeks of the diet, due to depleted glycogen stores and dehydration. It is indeed a fine idea to take it easy during the beginning of the transition to a low-carb diet while the body adjusts–however, after this period the body can handle exercise, and exercise is always recommended. Olympic biathlon gold-medalist Bjorn Ferry was on a low carb high-fat diet when he won his gold medal–point being a low carb diet does affect one’s ability to exercise beyond the acclimation period. Exercising increases HDLs (as reviewed by Kokkinos & Fernhall, 1999) and further reduces visceral fat stores (and subsequently LDLs). Exercising on a low carb diet is an important part of maintaining heart health.
Limit your alcohol intake
Some studies show that moderate alcohol consumption increases heart health by increasing HDL and antioxidant levels. However, high amounts of alcohol are long proven to be bad for the heart. Excess alcohol intake can raise triglyceride (fat) levels in the blood, raise blood pressure, cause cardiac arrhythmia, and even stroke. Many low carb dieters promote moderate alcohol consumption as a boost to the low carb diet, and cite that it increases metabolism. Moderate consumption may be healthy, just make sure to keep it moderate. Especially towards the beginning of the low carb diet, alcohol intake can cause dehydration and further reduce water levels in the dehydrating acclimation period to a low carb diet. Alcohol consumption also depletes nutrients in the body, which could exacerbate the malnutrition already present in a low carb diet. Moderating or eliminating alcohol intake while on a low carb diet will help increase heart health.
- Fung, TT; Van Dam, RM; Hankinson, SE; Stampfer, M; Willett, WC; Hu, FB (2010). “Low carbohydrate diets and all-cause and cause-specific mortality: Two cohort studies”. Annals of Internal Medicine 153 (5): 289–98.
- Freedman MR, King J, Kennedy E. Popular diets: a scientific review. Obesity Research 2001;9
- Kokkinos PF, Fernhall B (1999) Physical activity and high density lipoprotein cholesterol levels – What is the relationship? Sports Med 28:307-314.
More Articles on CarbSmart.com by Dr. Nicole Avena.