Study under review: A human model of dietary saturated fatty acid induced insulin resistance
Insulin resistance is the foundation for many of the diseases that afflict the developed world, including metabolic syndrome, cardiovascular disease, and type 2 diabetes. Accordingly, it should come as no surprise that a lot of research has investigated how and why insulin resistance develops.
One avenue of this research is among people with obesity, as dysfunctions in fat tissue metabolism are a central player in the development of insulin resistance, and having more fat increases the chance of something going wrong with it. However, people with obesity have a lot going on, which makes isolating the effect of any single variable on insulin resistance difficult. Similarly, while some researchers have overfed normal-weight people to mimic how obesity develops, these studies do not allow for the determination of any potential mechanisms underlying insulin resistance that occur before changes in body composition and fat mass.
More recently, researchers have experimentally induced insulin resistance in a matter of hours by infusing people with free fatty acids. Some of the potential mechanisms at play are shown in Figure 1. It has been known since at least the 1990s that elevated levels of circulating free fatty acids cause insulin resistance, but infusing free fatty acids is hardly representative of the real world. For instance, infused concentrations of free fatty acids far exceed what even the most insulin resistant people experience.
References: Castro, AV, et al. Arq Bras Endocrinol Metabol. 2014 Aug.
Chaurasia, B, Summers, SA. Trends Endocrinol Metab. 2015 Oct.
Studying insulin resistance and its development in humans can be tricky because of the numerous confounding variables present in people who are insulin resistant, including diet and lifestyle factors. The current study sought to develop a diet that rapidly induced insulin resistance among healthy people to avoid much of the “noise” that often accompanies insulin resistance development.
Other Articles in Issue #25 (November 2016)
Interview: Jasmina Aganovic
How much do you know about the bacteria that live on your skin? Whether or not you have skin issues, this interview is worth a look.
Skip breakfast, lose fat?
The most popular type of intermittent fasting among people who lift weights seems to be a 16 hour fast, followed by an 8 hour eating window. This is the first trial to test that protocol in a trained population.
Starches last for better blood glucose
Advice for blood sugar regulation ranges from "eat a balanced diet" to "beware carbs!". Macros and foods aside, could switching up the order in which you eat the same foods impact blood sugar?
A second look at protein quantity after exercise
Do muscular people require more protein after lifting? How much protein is needed to optimize muscle protein synthesis after a workout? This trial addressed both questions.
New data on vitamin D safety
Vitamin D supplementation would appear to have a pristine safety record, at least at first glance. This meta-analysis takes another look at that issue, specifically at potential effects on excessive calcium levels.
Can probiotics be used to treat multiple sclerosis?
The main supplement that’s been linked to helping MS is vitamin D. This probiotic trial could help inform whether gut microbiome approaches should be equally emphasized.
Interview: Julianne Taylor
Julianne is a New Zealand based nutritionist with a particular interest in autoimmune disease. Here, we pick her brain on what she’s found about the diet-disease connection. Julianne first trained as a registered general and obstetric nurse. She then retrained as a furniture designer, followed by a post-graduate diploma in design for disability in London. Back in NZ in the 1990’s Julianne designed, made, and fitted custom wheelchair seats and other aids for people with extreme physical disabilities.