Can an Alternate-Day High Fat Diet Turn You into a Fat Burning Machine (Boost Your Muscles' Oxidative Capacity)?

Whether the "alternate-day high fat diet" is in fact an alternative to "training low and competing high", which you can also tweak like this, appears questionable to me, but it is certainly interesting.

If you take a look at the contemporary "low carb"-hype, one of the often-heard arguments in favor of high(er) fat and low carbohydrate intakes is the notion that this would increase your cells' ability to bur fat... or, as some people phrase it: "A high fat diet will turn you into a fat burning machine!"

Believe it or not, this is not totally wrong. What is wrong, though, is that the increase in mitochondrial fatty acid oxidation capacity, which is an adaptive response to the lack of other energy sources, will translate into direct fat loss. Eventually, you will still only lose weight and body fat if you are in a caloric deficit: high carb, low carb or no carb - personal preferences and parameters may determine which one works best for you, but eventually both work.

Until further studies have been done, you better stick to real fasting?

Breakfast and Circadian Rhythm

Does Meal Timing Matter?

Habits Determine Effects of Fasting

Fasting Works - It Does, Right!?

Does the Break- Fast-Myth Break?

Breakfast? (Un?) Biased Review

But I am getting off an a tangent. The actual question in today's SuppVersity article is after all not, whether a high fat diet allows for easier, faster or more reliable fat loss than a balanced or high carb diet. No, the question for today's SuppVersity article is: "Can an Alternate Day High Fat Diet Provide Turn You into a Fat Burning Machine?"

A hilarious idea, right? Well, I would probably have said the same before I had read a recent study from the Waseda University in Japan (Li. 2016). In said study, Li et al. tried to elucidate whether they would be able to get the same improvements in mitochondrial enzyme activity and protein content others have observed in rodents on high fat diets without the concomitant long-term intra-abdominal fat accumulation, and ever-increasing insulin resistance, and obesity. Put simply, Li et al. wanted to know if a small tweak to the diet would be able to "induce increases in mitochondrial oxidative capacities in skeletal muscle without intra-abdominal fat accumulation and body weight gain," as it would "offer many advantages" to endurance athletes (Li. 2016). Their hypothesis was that

• feeding a high fat diet every other day would trigger the increase in free fatty acids (FFA) that's necessary to produce the desirable increases in mitochondrial capacity, while
• feeding a regular (low fat) diet on the other day would help to ameliorate (or even better block) the accumulation of intra-abdominal fat mass. 

Accordingly, the scientists conducted a study in which male wistar rats were fed an alternate-day high-fat diet, with a lard, corn oil, sucrose, and casein based HF diet (32%, 18%, 27%, and 23%, respectively, of total calories | 5.1 kcal/g) on one and standard rodent chow (59% carbohydrate, 12% fat, and 29% protein | 3.4 kcal/g) on the other day.

Figure 1: Visceral (epididymal) fat mass, plasma glucose, fatty acid and insulin levels and relative difference to control (above bars); mind the multiplicators that were necessary to plot all data in a single graph (Li. 2016).

As you can see in Figures 1 & 2 the scientists achieved their goal. The visceral fat gain was sign. ameliorated. In spite of identical body weights, the rodents who had been fat high fat diets on alternate days were yet still fatter than their peers on the control diet.

Figure 2: Levels of markers of mitochondrial oxidative capacity after the treatment period (Li. 2016).

To know whether this increase in visceral fat was worth it, one would need to know whether the increases in citric acid synthetase (CS), beta-HAD, PGC-1a and LCAD activity actually pay off in form of increased endurance and/or performance gains due to an increased oxidative capacity.

Figure 3: Effects of alternate‐day high‐fat diet feeding on glycogen concentration (A) and GLUT‐4 protein content (B) in rat skeletal muscle. Values are mean ± SEM of 6 animals per group // If we go by the effects on glycogen, GLUT-4 and insulin (see Figure 1), the ALT diet should not impair the use of CHOs in athletes and would thus allow for CHO fueling during competition, but that's, as much about ALT, in theory!

Bottom line: In view of unaltered glycogen levels and slightly, but non-significantly increased levels of glucose transporter 4 (GLUT-4 | see Figure 3) levels in the muscle tissue of the ALT rats, it is likely that these performance changes would have been observed, but Li et al. don't have the data to prove that they exist.

For the average endurance athlete of whom the scientists rightly write that he does not adopt a high fat diet, even though it may increase the mitochondrial enzyme activities and decrease the utilization of glycogen during endurance exercise, Li's study is thus of very limited value, because future studies are necessary to prove the practical efficacy and relevance of an "alternate-day high fat diet" that has been tested only in rodents and how it compares to "training low and competing high" (Burke. 2010) | Comment!

References:

• Burke LM. Fueling strategies to optimize performance: training high or training low? Scand J Med Sci Sports. 2010 Oct;20 Suppl 2:48-58. doi: 10.1111/j.1600-0838.2010.01185.x.
• Li X, Higashida K, Kawamura T, Higuchi M. Alternate-Day High-Fat Diet Induces an Increase in Mitochondrial Enzyme Activities and Protein Content in Rat Skeletal Muscle. Nutrients. 2016 Apr 6;8(4). pii: E203.