What Should Doctors Tell Their Patients About Low Carb Diets?

While several decades ago, the “low fat” diet was the ideal that people were told to aim for, nowadays this has largely been taken over by a “low carb” craze. Various low carb diets, including the Atkins Diet, South Beach diet, Paleo diet and ketogenic diet have been sweeping the country, and chances are good that many doctors now going into practice are going to have to field questions from their patients about these diets and whether or not they are a) effective and b) safe.

This article covers clinical evidence which shows the apparent advantages – and disadvantages – of a “low carb” diet so that doctors will have a better understanding of when this kind of eating regimen might – or might not – be appropriate.

Advantages of a Low Carb Diet
Low carb diets are popular for a reason – and there is strong clinical evidence to show that there are many advantages to this style of eating, including weight loss, better glycemic control for those with diabetes and (possibly) an improvement in markers for cardiac disease.

By far, the reason which so many people choose to go on a low carb diet is to lose excess weight – and with two-thirds of Americans now overweight or obese, most doctors, dietitians and other medical professionals agree that some drastic changes are necessary to the American diet to help combat this growing epidemic. In one study, which was published in the journal Nutrients in 2013, it was found that low carb/ketogenic diets, alternating with a Mediterranean-style diet with moderate carb intake was helpful for long-term weight loss and avoided the “yo-yo” dieting which so many patients struggle with.

Glycemic control is another reason often touted by proponents of low carb diets. According to the American Diabetes Association, there are around 29.1 million diabetics in the United States and that number is only predicted to increase in coming years; therefore, finding a diet regimen that will help those with this condition achieve better management is incredibly important. In one study of Type 1 diabetic patients, carb counting and carb restriction, over the course of two years, helped to lower the AIC levels of the majority of the participants and in many cases also led to an increase in higher levels of healthful HDL cholesterol levels, an important marker for heart health. Other studies on Type 2 diabetics have also found improvement in glycemic control.

Other proponents of this diet promote it as a means of achieving better heart health. In one study of participants already taking statins to reduce cholesterol levels, researchers wanted to see if a carbohydrate-restricted diet would provide them with even more benefits. Participants adhered to a 46% carb/36% fat/ 17% protein diet and compared to their baseline measurements, showed lower blood pressure, improved circulation, lower serum triglyceride and insulin levels, among other markers in this study. Researchers concluded that “individuals undergoing statin therapy experience additional improvements in metabolic and vascular health…as evidenced by increased insulin sensitivity, vessel endothelial function, decreased blood pressure and triglycerides and adhesion molecules”. In short, many researchers believe that low carb diets can help promote a healthier heart – which is incredibly important, seeing as heart disease is still, according to the American Heart Association, the number one killer of Americans.

Disadvantages of a Low Carb Diet
There are good reasons, however, why low carb diets have so many critics, especially those who are concerned with the fact that many low carb diets restrict foods such as legumes and whole grain products that have been proven to promote human health or worried that the high “sat fat” foods that some of these diets permit might increase risks for heart disease development – as well as that of other serious, chronic conditions.

In one study out of Norway, researchers there note that the low carb craze has led many Norwegians to increase their intake of products like butter and bacon while turning away from more traditional Scandinavian foods like brown bread or root vegetables like carrots. The scientists sought to examine the effects of these dietary changes by following patients on a 4 week low carb but high fat diet. What they found was that this diet considerably raised both total cholesterol and LDL cholesterol levels (both important markers for cardiac health) in these participants. It should be said, however, that the researchers themselves acknowledge the limitations of this study: there were only 7 participants and the study only took place over the course of 4 weeks. However, research like this can reinforce the concern that many healthcare professionals have about a diet which allows such a high intake of saturated fats. However, it important to note that other studies have found unwanted long-term risks for low-carb diets, including one published in the Asia Pacific Journal of Clinical Nutrition which reviewed other studies on carbohydrate restrictions and found that it had been linked to cardiac arrhythmias, impairment of cardiac contractility and lipid abnormalities.

Also, although proponents of low carb diets for weight loss believe that this sort of eating program gives a “metabolic advantage” and facilitates the shedding of excess fat, a review published in the Journal of the American Dietetics Association found that while some studies did show this advantage, other studies did not find this to be the case. From their review of studies, the researchers concluded that the best clinically proven diet for long-term weight loss was one which was moderate in carbs (comprising 35-50% of the diet), moderate in fats (comprising around 25-35% of the diet) and moderate in proteins (comprising 25-30% of the diet). In short, what these researchers found is that a balanced diet works best in the long term for healthy weight management. It is important to note that, though some studies have shown improvements in weight and cardiac health, three important health organizations – the American Heart Association, the American College of Cardiology and the Obesity Society – do not believe that there is enough evidence to support the supposition that low carb diets are heart health or offer long-term weight loss solutions. The Mayo Clinic, too, notes that while low-carb diets do appear to help significantly with short-term weight loss, that this advantage disappears in the long-term. What does not disappear, the clinic notes, is the long-term risks that carbohydrate restriction can bring with it, including increased risk for vitamin deficiencies, osteoporosis and ketosis.

What Do You Tell Patients?
At this point, many doctors-to-be might be wondering just what to tell their patients about this new trend in dieting. With some studies showing conflicting results and some results showing cause for concern, doctors should likely be circumspect in how they tout a low carb diet to their patients: while there do appear to be benefits in regards to weight management and glycemic control, other studies continue to show cause for concern.

In regards to concerns about cholesterol levels, one important point that doctors should make to their patients is that “low in carbs” does not necessarily mean “high in fat” and that, especially for those who have issues with hypercholestremia, efforts should be made to follow a diet that is low in saturated fats, emphasizing fats coming from such sources as olive oil and almonds, both of which have been proven to promote heart health. In short, a low carb diet should not be seen as a free for all pass on bacon, cream and other items high in saturated fats.

In regards to diabetic patients, many doctors have concerns that extreme carbohydrate restrictions, coupled with current doses of diabetic drugs (either insulin or oral hypoglycemic medications) may lead to episodes of hypoglycemia. If a diabetic patient is contemplating such a diet, dosage adjustments may need to be made to prevent this from happening. It should be noted, however, that the ADA does not endorse low carb diets as a means of achieving blood sugar control and that in fact, the ADA diet allows for whole grains, legumes and other foods that many low carb diets restrict.

Doctors should also consider educating their patients on the benefits of a balanced diet for long-term weight maintenance and promotion of cardiac and general health and that more emphasis should be put on a combination of a this balanced diet with regular exercise and other lifestyle habits to form a holistic approach to health management. Fielding questions about low carb diets – and diets in general – can offer a good segue into this kind of important discussion.

The takeaway here is that low carb diets, like any other trendy eating regimen, are not “silver bullets” and do not correct other systemic problems like lack of exercise, failure to drink adequate water, poor stress management or underlying medical conditions such as a thyroid imbalance which may be in part responsible for weight gain. Like any other diet, it should be used with caution and only after consulting with a physician (and possible dietitian as well) in order to fully understand the risks and benefits and to make an informed decision about whether or not to follow a low carb diet or to opt for a more traditional calorie- and fat-restricted eating plan.

References

Ballard, K.D. et. al. Dietary Carbohydrate Restriction Improves Insulin Sensitivity, Blood Pressure,
Microvascular Function and Cellular Adhesion Markers in Individuals Taking Statins.
Nutrition Research. 2013 33(11) 905-12

Baumann, M. Lipid Profile of Healthy Persons with Low-Carbohydrate Diet. Tidsskr Nor Laegforen.
2013. 183(11) 1193-6

Bilsborough, S.A. and Crowe, T.C. Low-Carbohydrate Diets: What are the Potential Short- and Long-Term
Health Implications? Asia Pacific Journal of Clinical Nutrition. 2003. 12(4) 396-404
Diabetes Basics. American Diabetes Association. 2015.
www.diabetes.org/diabetes-basics/?loc=db=slabnav

Goshen. D. et. al. Effects of Carbohydrate Counting Method on in Children with Type 1 Diabetes
Mellitus. Journal of Clinical Research. 2014. 6(2) 74-78
Healthy Lifestyle: Weight Loss. The Mayo Clinic. 2015.
www.mayoclinic.org/healthy-lifestyle/weight-loss/in-depth/low-carb-diet/art-20045831?pg=2

Paoli, A. Long-term Successful Weight Loss with Combination Bi-Phasic Ketogenic Mediterranean Diet
and Mediterranean Diet Maintenance Protocol. Nutrients. 2013. 5(12) 5705-17

Schoelk, D.A. and Buchholz, A.C. Energetics of Obesity and Weight Control: Does Diet Composition
Matter? Journal of the American Dietetics Association. 2005. 105 (5) 24-8