Carbohydrates

Carbohydrates function as the main source of cellular (Body) energy from the human diet, and are particularly essential to supplying energy to the glucose-dependent brain and nervous system.PMID: 32119432

Carbohydrates contain carbon, hydrogen, and oxygen in the ratio of 1:2:1.
The starch is protected from digestion. The presence of organic acids slows gastric emptying.
Fibre or non-starch, leading to production of short chain fatty acids to influence hepatic insulin sensitivity.PMID: 25770259

Refined carbohydrates can be a problem due to the rapid spikes in insulin? However, it’s obviously not the insulin because protein can cause rapid spikes in insulin as well.  One issue with refined carbohydrate is a problem of energy density.  With refined carbohydrate, it is easier to pack many calories into a small package.  Not only that, but foods with high-energy density are often not as satiating as foods with low-energy density.  In fact, when it comes to high-carbohydrate foods, energy density is a strong predictor of a food’s ability to create satiety (i.e., low-energy density foods create more satiety).  There are other issues with refined carbohydrate as well that are beyond the scope of this article.

How many carbohydrates a person can tolerate depends a lot on individual neurotransmitters (neurochemistry). It is genetically determined to which neurotransmitters the body is more sensitive to. People who are dopamine dominant will have a higher need for carbohydrates and can handle simple carbohydrates better. Those who are serotonin dominant have a generally higher carbohydrate tolerance. Hence, the need for carbohydrates is strongly personal.

Two major gene adaptations occurred in average salivary amylase gene copy number (AMY1) increased more than threefold related to starch consumption.PMID: 17828263 

Lactase into adulthood, facilitating digestion of the milk sugar lactose. PMID: 28426286

Expensive Tissue Hypothesis:relates brain and gut size in evolution.
Cooking Hypothesis:The “cooking hypothesis” is a relatively new theory on human evolution that proposes that our brain became significantly larger than our ancestor’s because of cooking with fire.
Savannah Hypothesis:This theory suggests that the shift towards a diet rich in carbohydrates and other plant foods occurred when early humans moved out of the dense forests and adapted to the savannah environment. 
Aquatic Ape Hypothesis:The aquatic ape hypothesis is a controversial idea that the ancestors of modern humans adapted to a more aquatic habitat.
Gut Microbiome Hypothesis:childhood exposure to pathogenic organisms, especially certain bacteria, is essential for training the immune system to become tolerant of the many neutral or benevolent strains of microbiota that enter or reside in our bodies; without this exposure, the immune system overreacts to environmental cues.

Due to evolution, the brain began to enlarge, demanding more energy to sustain its growth and cognitive abilities, but the body was having limitation to process and extract energy from food, hence larger G.I was necessary to extract enough energy from a low-energy-density diet. Carbohydrates are a source of easily accessible and rapidly available energy, provided an evolutionary advantage which allowed humans to divert major energy sources away from the digestive system towards the development and functioning of the brain. This energy saving, in turn, allowed the brain’s high-energy demands to grow and evolve while maintaining a smaller, more energy-efficient gastrointestinal tract.

Refined grains are processed to remove the protein and fat rich germ and
fibre rich bran, leaving only the starchy endosperm.

Potatoes they contain predominantly starch with a high GI as typically eaten.PMID: 18835944
In three cohorts of US men and women, increased intake of potatoes was associated with greater weight gain.PMID: 21696306
Higher risk of type 2 diabetes, even after adjustment for body mass index and
other diabetes risk factors.PMID: 26681722
In cohorts, higher intake of baked, boiled, or mashed potatoes and French fries was independently associated with an increased risk of developing hypertension.PMID: 27189229

In 2011,   a 6-month RCT Study showed, people consuming sugar sweetened drinks had higher levels of liver and ectopic fat than those consuming drinks without added sugar, even though body weight did not differ by diet group.PMID: 22205311
The 2015-2020 Dietary Guidelines for Americans recommend a limit on added sugars of 10% of total energy.PMID: 26773024

The diploid Copy number of the salivary amylase gene (AMY1) varies widely. People with higher copy numbers have higher postprandial glycaemia after
consumption of starchy (but not sugary) foods.PMID: 30239565
High AMY1 copy number may have provided a survival advantage, its relevance to obesity and metabolic disease today remains unclear.PMID: 26098870 PMID: 24686848
Study, a diet-gene interaction the lowest body mass index among people with high starch intake and low AMY1 copy number (reflecting low genetic capacity to digest starch).PMID: 28539377 

NO

A 2007 10, Double-blind, RCT Crossover Study Showed (#untrained Men) Protein without carbohydrates can still maximally increase protein synthesis rates.PMID: 17609259

A 2015 Untrained Men, RCT Crossover 12 Weeks Study, Showed Consuming protein without carbohydrates post-workout has been shown to offer similar gains in the long term compared to protein + carbs.PMID: 26677350

YES

A 2016, 2018 Study Shows, Carb cycling first became popular in endurance training as it was shown to potentially enhance adaptations to endurance exercise.
Muscle glycogen content can also modulate transcription factors that may affect the protein synthesis process.PMID: 29453741 PMID: 27897989

2005,2008, 2010,2011 RCT Study Shows, training in a glycogen-depleted state has been shown to enhance the expression of genes that promote the creation of mitochondria.PMID: 15361516 PMID: 20351596 PMID: 21051570 PMID: 18772325

2015 Study Shows, increasing mitochondrial density in the muscle cell can improve the energy efficiency of the muscle cell, increase fat oxidation, and improve endurance performance.PMID: 26112242

2016 RCT 3-week Study Shows, Study found that the carb cycling group lost significantly more fat than the control group.PMID: 26741119

There are short-term performance benefits with carb cycling, but most of these studies are 3-weeks in length or less. Other studies that show changes in gene expressions are acute studies, (examining one or a few training sessions).
We don’t know if there’s long-term performance benefits to carb cycling.
Changes in gene expression would obviously influence long-term adaptation.
Most of the research is on endurance athletes & not on strength athletes.
We still don’t have many longitudinal studies.

Yes

A 1991 (1 Eight Male Subjects, Leg Extension Exercise,70% 1-RM) 1999 (8 Bodybuilders, Arm-curl Training Session,80% 1-rm) Studies Showed, lifting weights causes a decent amount of glycogen depletion.PMID: 10364416 PMID: 2055849

2005, 2008, 2011 Studies Showed increasing carbohydrate utilization during a workout can actually increase fat, burning the rest of the day.PMID: 15361516 PMID: 18772325 PMID: 21411835

2009 Study, performing a heavier/higher volume session in the morning, avoiding carbs all day, and then doing a lighter session in the evening while carb-depleted can increase whole body fat burning. PMID: 19265068

NOTE:  since your heavy workout is in the morning, eating some carbs before bed can help increase muscle glycogen content for that heavy workout. You can still eat carbs after your evening session.

You can check for diabetes by measuring the amount of glucose in your blood. In order to test and monitor blood glucose, blood is usually taken when the patient has fasted for at least 8 hours.
A healthy fasting blood glucose level is less than or equal to 99 mg/dL. Someone who is more likely to get diabetes, or prediabetes, has a fasting blood glucose of 100 to 125 mg/dL. If a patient has a fasting blood glucose of 126 mg/dL or more, they can be diagnosed with diabetes.PMID: 12186517 PMID: 20353144