Low-carb diets found to be slightly better for weight loss in the short-term, compared with low-fat diets.
The plethora of diets on the weight loss market is often confusing. Low-carb diets, in particular, go under numerous names - such as Atkins, South Beach, Paleo, and Ketogenic. So which of these is the best option for weight loss? Are the diets safe, and is there a huge difference in results between them?
The Mayo Clinic in Arizona aimed to review studies that examine low-carb diets, in order to find out if they are safe and effective for weight loss, and cardiovascular and metabolic health. They published the results of their study in The Journal of the American Osteopathic Association.
Depending on the diet, the physicians found that the definition of low-carb diet is highly variable. Previous studies have shown low-carb diets as comprising less than 45 percent of daily calories from carbohydrates. However, this figure is not dissimilar to the typical Western diet that has more than 50 percent.
While all of the reviewed diets were based on the idea of carbohydrate restriction, the allowed carbs accounted for anywhere between 4-46 percent of daily calories, which the researchers say "convolutes the evidence."
Physicians advise eating 'real foods,' not highly processed meats
An analysis of 41 trials that evaluated the effects of low-carb diets on weight loss revealed that participants lost between 2.5-9 more pounds than individuals who followed a low-fat diet.
"The best conclusion to draw is that adhering to a short-term low-carb diet appears to be safe and may be associated with weight reduction," says Dr. Heather Fields, an internal medicine physician at Mayo Clinic and lead researcher on this study.
"However, that weight loss is small and of questionable clinical significance in comparison to low-fat diets. We encourage patients to eat real food and avoid highly processed foods, especially processed meats, such as bacon, sausage, deli meats, hot dogs, and ham when following any particular diet," she adds.
To analyze the potentially harmful effects and safety of low-carb diets, Fields and colleagues looked at research conducted between January 2005 and April 2016. People tend to eat more meat when carbohydrates are restricted, which could increase the risk of death from all causes, including cancer.
Most of the studies failed to provide the source or quality of proteins and fats consumed in the low-fat diets, making it difficult to draw conclusions linking excessive meat consumption to all-cause mortality and increased cancer risks.
"Physicians must keep in mind that the literature is surprisingly limited, considering the popularity of these diets and the claims of health benefits in the public press. Our review found no safety issues identified in the current literature, but patients considering low-carb diets should be advised there is very little data on long-term safety and efficacy," Field notes.
Low-carb diets may provide short-term weight loss satisfaction
Field notes that drawing broad conclusions proved difficult due to various limitations within the research. Some of the studies did not include information on the type of weight lost, such as whether it was fat, muscle, or water. Also, many of the studies relied on participants recalling foods and beverages they had consumed, which can be subject to error.
Dr. Tiffany Lowe-Payne, an osteopathic family physician, points out that several factors can affect a person's success with weight loss, including genetics, personal history, and their ability to stick to the diet.
"As an osteopathic physician, I tell patients there is no one-size-fits-all approach for health. When you think of what dieters want - and what they need to stay motivated - it is the satisfaction of results. They want to see significant weight loss and fast. For many, a low-carb lifestyle provides the answer they are looking for."
Dr. Tiffany Lowe-Payne
Dr. Lowe-Payne recognizes that carbohydrates make up a considerable part of many people's diets. She also highlights that after 6 months, weight loss is virtually the same for individuals regardless of whether they are on a low-carb or low-fat diet.
For patients who are trying to lower their blood sugar levels or manage insulin resistance, low-carb diets have been shown to be beneficial, Lowe-Payne concludes.