A few things: 1) Carbs are the worst source of high energy calories because of simple math: there are only 4 kcal/gram while fat has 9 kcal/gram. High quality fats are also better energy because they lasts longer and don't initiate a glycemic response from the pancreas, which is dangerous (diabetes) as well as annoying (you need to eat again sooner). Burning primarily carbs is a vicious cycle, while burning ketones is a stable source of energy that our pre-historic ancestors thrived on.
2) All bread is not created equally. Most bread consumed in America is completely non-nutritious, which makes them empty calories. "Empty" implies that there are MACROnutrients in the food, but not MICROnutrients. The idea is to only eat macronutrients that are densely composed of micronutrients, hence the term "nutrient dense", which is a term all too often forgotten when someone says that calories are what matters. Fats from wild or completely pastures animals are densely packed w vitamins, so it meets this criteria.
3) For bread to be even arguably nutritious, it needs to meet the following criteria:
-Organic grains that were purchased whole and milled just before mixing into dough (pesticides are neurotoxins; whole grains still have their natural oils, nutrients and fiber; and most pre-milled flours have rancid oils that create free radicals in the body and destroy nutrients in grain). -Ingredients should only be flour, water, salt and wild yeast. Most breads have a number of others ingredients that are non-nutritious and potentially hazardous (rancid oils, preservatives, high-fructose corn syrup, etc. Of course, other additions like walnuts or flax seeds are fine...) -Dough should be wet, starting out almost like soup, to have the appropriate grain-to-water ratio (so the grains don't soak up your stomach acid and bloat your belly). -Dough should be fermented for 24 hours using wild yeast in stead of commercial yeast and should not contain any sugar (fermentation releases the key nutrients and allows the microbiota to eat most of the starches and proteins, and omitting sugar reduces the glycemic affect of the bread).
There's a bakery in Portland, OR that makes bread this way, as well one in CA. There are probably others...they're worth looking for because the bread is an entirely different experience than anything on the shelves of most bakeries or grocery stores......and it makes Subway bread look like a Frankenfood. At the end of the day, though, any nutrition sought in bread can be found in much more nutritious foods like fibrous veggies and 100% pastured animal fats.
https://en.m.wikipedia.org/wiki/Ketogenic_diet https://www.sciencedaily.com/releases/2015/11/151117091234.htm http://www.askmen.com/news/sports/ketogenic-diet.html https://www.google.com/amp/www.mensfitness.com/nutrition/what-to-eat/truth-behind-worlds-most-cutting-edge-fat-burning-performance-meal-plan-keto/amp http://www.marksdailyapple.com/the-fat-burning-brain-what-are-the-cognitive-effects-of-ketosis/ https://www.amazon.com/Primal-Fat-Burner-Super-Power-High-Fat/dp/150111641X http://www.taborbread.com/ http://michaelpollan.com/books/cooked/