- A recent review Running in the Cold Heres What the Keto Diet Can Do to Your Speed Study Says VO2 Max Better Health Marker Than BMI.
- They found that long-term, carb-restrictive diets had no benefit over other types of diets for weight loss.
- Low-carb diets, such as keto, may also restrict intake of other nutrient-dense foods that are important for heart health.
A recent review Running in the Cold Heres What the Keto Diet Can Do to Your Speed looked at how low-carbohydrate (10 to 25 percent of total daily calories from carbs) and very low-carb diets (less than 10 percent of total daily calories from carbs, including the ketogenic diet) affected body weight and other cardio-metabolic risk factors, such as blood lipids, glycemic control, and high blood pressure.
What the National Lipid Association found was that following a very low-carb diet, such as keto, for an extended period of time had no long-term advantages. What’s more, the keto diet and other carb-restrictive diets actually may severely restrict nutrient-dense foods that can offer cardio-metabolic benefits, explained co-authors Carol Kirkpatrick, Ph.D., R.D.N., Director and Clinical Associate Professor at Idaho State University, and Kevin C. Maki, Ph.D., C.L.S., Adjunct Professor in the Department of Applied Health Sciences at the School of Public Health at Indiana University Bloomington.
The review found that while those following keto diets may see more short-term weight loss than those following low-fat diets, after 12 months or more, there is no difference in weight loss. That said, long-term compliance with these diets can be challenging, and the long-term risks—and benefits—of low-carb diets, especially keto, are not yet fully understood, noted Kirkpatrick and Maki.
Starting very low-carb diets like keto can also come with some serious side effects. People may experience symptoms known as the “keto flu,” which includes lightheadedness, dizziness, fatigue, difficulty exercising, poor sleep, and constipation, said Kirkpatrick and Maki.
When it comes to cholesterol, the effect of very low-carb and ketogenic diets on LDL (“bad”) cholesterol is variable. Some individuals may see an increase in LDL levels with these diets, especially due to high intakes of saturated fatty acids and dietary cholesterol. Thus, baseline and follow-up lipid/lipoprotein assessments are recommended for individuals choosing to follow these diets, said Kirkpatrick and Maki.
It’s also important to note that very low-carb or keto diets are not for everyone. People with type 2 diabetes may experience hypoglycemia (low blood sugar) if they don’t adjust their medication, and those who take vitamin K-dependent anticoagulants may need more frequent monitoring due to a potential change in vitamin K intake. It’s not recommended that people who have elevated blood levels of cholesterol try the diet, and those who have atherosclerotic cardiovascular disease, a history of atrial fibrillation, or the presence or history of heart failure, kidney disease, or liver disease should talk with their doctor before trying the diet.
On the flip side, low and very low-carb diets lowered triglyceride levels in study participants compared to those following high-carb, low-fat diets. And while these low-carb diets increased HDL (good) cholesterol levels in the short term, the beneficial effect diminished after six months or longer, especially in people with type 2 or pre-diabetes, said Kirkpatrick and Maki. There was also a reduction in the use of diabetes medication when people with type 2 diabetes followed low-carb diets, but the carb intake was not low enough to be considered a keto diet.
Current evidence supports that a low-carb diet or moderate-carb diet (26 to 44 percent of total daily calories), may benefit individuals who are overweight or obese in the short term (two to six months) to kickstart weight loss, people with type 2 diabetes, and to lower triglyceride levels and help increase HDL cholesterol, explained Kirkpatrick and Maki
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While fitness or physical activity performance was not reviewed for this statement, current evidence does not support that very low-carb or ketogenic diets are more beneficial for fitness or physical activity performance in either recreational or elite athletes and, in fact, have resulted in decreased performance in some athletes, explained Kirkpatrick and Maki.
The ideal dietary pattern to promote weight loss, as well as cardiovascular health, fitness, and general health depends on the person striving to lose weight. It’s important to take into consideration personal preferences and behavioral, family, cultural, and social dynamics, as well as ethnic or economic influences, the researchers added.
But, if you’re looking to clean up your diet and don’t know where to begin, the diet that has the most evidence to date to support weight loss and have beneficial health effects, such as lowering cardio-metabolic risk factors is the Mediterranean diet, which involves eating lots of fresh vegetables and fruits, whole grains, seeds and nuts, legumes, and fish or seafood, as well as moderate carb intake.
