Here we go again. A new study appears to link high fat intake to insulin resistance and postmeal blood sugar spikes. All study participants had Type 1 diabetes and were assigned to consume either two low-fat meals and one high-fat dinner or three low-fat meals. Researchers reported that those receiving the high-fat dinner required more insulin (12.6 units vs. 9 units for the low-fat dinner) and that their postprandial blood sugar and insulin levels were higher and stayed high for several hours after eating.
There are a few red flags regarding this study. First of all, the sample size was extremely small (seven people). And this line is revealing:
"The two dinners received by each subject had identical carbohydrate and protein content but they differed in fat content (10 grams vs. 60 grams)."
Now, the amount of carbs each meal contained wasn't reported (or at least I couldn't find it), but the amount of calories was. So by doing some math, we can get a ballpark estimate:
The low-fat dinner contained on average about 600 calories, 10 grams of fat (90 calories), and let's say 25% protein (38 grams, 150 calories), which is probably being generous. That would leave approximately 90 grams (360 calories) of carbohydrate to make the 600 calorie total.
So given the high carbohydrate content of the meal, these results aren't surprising. Fat delays the absorption of carbohydrate and makes accurate dosing of insulin extremely challenging (as CDE Gary Scheiner explains in discussing how to bolus for pizza). Previous studies have demonstrated the deleterious metabolic effects of consuming a high-fat, high-carbohydrate meal, which include insulin resistance, delayed postprandial hyperglycemia, and elevated triglycerides.
However, there is research indicating that a high-fat, low-carbohydrate diet does not produce the same response; in fact, it results in lower insulin needs, less insulin resistance, and better postmeal blood sugar and lipid response in both Type 1 and Type 2 diabetes. And there's enough anecdotal evidence to support these findings many times over.
So this study simply confirms what we already know: The combination of high fat and high carbohydrate is unhealthy. The best chance people with diabetes have of achieving better blood sugar control and decreasing insulin needs is to adopt whatever form of carbohydrate restriction works best for them.
1. Volek JS, et al. Carbohydrate restriction has a more favorable impact on the metabolic syndrome than a low-fat diet. Lipids 2009 Apr;44(4):297-309.
2.Volek JS, et al. Effects of dietary carbohydrate restriction vs. low-fat diet on flow-mediated dilation. Metabolism
3. Nielson JV, et al. Low carbohydrate diet int type 1 diabetes, long-term improvement and adherence: a clinical audit. Diabetol Metab Syndr 4: 23, 2012
Last week I received an e-mail from the editor of Diabetes Voice, a publication of the International Diabetes Federation, the organization comprised of diabetes associations around the world, including our own ADA. I've been asked to participate in a friendly written debate regarding low-carbohydrate diets in the Type 1 adult population and have gladly accepted! The debate will be published in late spring, just in time for the annual ADA conference in June. The opposing voice is an RN CDE, and we will each write a short (800 words or less) piece addressing the following:
"Debate: How low can you go?
The low-down on the low carbohydrate debate in Type 1 diabetes nutrition
As a means of representing relevant issues to the diabetes community, Diabetes Voice will be providing a forum in which experts can examine controversial issues and provide an argument supporting their point of view. The low carbohydrate debate marks the first in our series.
Since the advocacy of intensive insulin therapy following the Diabetes Control and Complications Trial, people living with Type 1 diabetes have been subjected to broad nutrition and dietary advice, with varying opinions on the recommended total daily intake of carbohydrate. Current American Diabetes Association (ADA) guidelines suggest a flexible range of carbohydrate, protein, and fat tailored to meet individual preferences, emphasizing the need to monitor and match insulin to carbohydrate intake as a means for achieving glycemic control below or around an HbA1c of 7%. More rigorous goals (<6.5%) are recommended for healthy younger people who have been recently diagnosed.
While low carbohydrate diets are recommended for weight loss as an effective short-term (up to 2 years) measure, there is less clarity regarding the utilisation of very low (>30 g/day), or low carbohydrate (30-105 g/day) intake. According to the ADA guidelines, the moderately low recommended daily allowance (RDA) for carbohydrate intake (130 g/day) is “an average minimum requirement.” Many people complain that maintaining even a moderately low carbohydrate diet is counterproductive, making glycemic control difficult to achieve, especially when considering the targets for post-prandial excursion (1-h postmeal: ≤140 mg/dL (7.8 mmol/L) or 2-h postmeal: ≤120 mg/dL (6.7 mmol/L)). Many patients, especially those on insulin pump therapy, have opted out of a diet based on 50%-60% carbohydrate intake, and an ‘underground movement’ has prompted some endocrinologists with large numbers of Type 1 patients to support their efforts.
We have asked our experts to weigh in and answer the question:
Can a nutritional regimen based on low carbohydrate intake provide safe and more effective glycemic control for a healthy Type 1 diabetes patient?"
Needless to say, I'm very excited about this opportunity. It's very encouraging that such a large and respected organization is providing a platform for a pro-low-carborbohydrate viewpoint. Definitely cause for celebration!
Yesterday I learned of a recent blog post by the Joslin Diabetes Center regarding my ADA Diabetes Spectrum article on the benefits of a whole-foods-based, low-carbohydrate diet for people with diabetes. (It's still not accessible to the public, but it should be within the next couple of months). While I appreciated the few positive remarks, I was disappointed by the overall message that we need grains and starchy vegetables in order to have a balanced, nutritious diet that people can follow indefinitely.
First of all, the recommendations I made were for a carbohydrate amount considerably higher than I currently follow or think is necessary for many people. While I don't have the time or inclination to go point by point over every statement made, there are a few things I'd like to address:
1. Grains and/or starchy vegetables are not necessary to ensure adequate micronutrient intake.
The post included my table containing a sample day's menus and nutrient analysis for select vitamins and minerals. Space considerations did not permit me to list additional nutrients or calorie counts (I originally submitted four tables with different menus and calorie counts but was told I could choose only one).
Fortunately, I still had the complete nutritional analysis for this day on FitDay (impressive, as this was a whole year ago) and found that it exceeded or came close to the RDA for the micronutrients in question:
Yes, the day was a little low on thiamin. Pork is the best source of thiamin, but I'm not necessarily suggesting people eat it every day. However, by slightly increasing the amount of nuts or animal protein, a person would easily meet the RDA . Also, consider the 10 Best Sources of Thiamin. Not a grain or starchy vegetable among them!
2. The fat content of this menu may be "elevated beyond the culinary comfort of most Americans," but that doesn't mean it is unhealthy or that a higher-fat diet would be difficult to adapt to.
I've discussed the issue of dietary fat in a previous blog post, and I have several references in my Diabetes Spectrum article regarding the lack of evidence that a high-fat diet contributes to heart disease or has other detrimental effects on health; on the contrary, such a diet may have a beneficial effect on lipid profiles and markers of inflammation. I believe a person with diabetes or metabolic syndrome following a "healthy, low-fat diet" that includes a breakfast such as a bowl of cereal with a banana and skim milk would achieve better blood sugar control and experience increased satiety by switching to the breakfast in the menu above and eating similar high-fat, moderate-protein, low-carb meals on a daily basis. This can be a very luxurious and satisfying way of eating.
3. Some people may find low carb difficult to stick to, but that doesn't mean it shouldn't be offered as an option for those who are interested in following it.
There is a well-known study indicating that a carb-restricted diet can be sustained over two years, but most studies are of much shorter duration. Unfortunately, the most difficult part of low carb is often at the beginning, when a person becomes adapted to using fat rather than glucose as a primary fuel source. There are many examples online of low-carb adherents -- including doctors, nurses, dietitians, and other healthcare professionals -- who have experienced great improvements in glycemic control and/or weight and find this way of eating enjoyable, energizing, and sustainable. I am one of them, and I will continue to advocate carbohydrate restriction as an alternative to the low-fat diet, higher-carbohydrate diets currently promoted by the majority of nutrition professionals.
Franziska Spritzler, RD, CDE