This is true for two reasons. Not only are many fad diets low fat, but they are also low calorie. Your body is not stupid! It can see that you are not taking in enough energy to support your basal metabolic rate. Your basal metabolic rate is the number of calories that your body requires to run your heart, brain, liver, digestive system, lungs etc. This critical number is very responsive to the environment because back in the good old days food wasn’t widely available. If you weren’t able to find food for a few days then your whole system slowed down to require less calories and protect you from dying.
The progression of nephropathy in patients can be significantly slowed by controlling high blood pressure, and by aggressively treating high blood sugar levels. Angiotensin converting enzyme inhibitors (ACE inhibitors) or angiotensin receptor blockers (ARBs) used in treating high blood pressure may also benefit kidney disease in patients with diabetes.
These diabetes complications are related to blood vessel diseases and are generally classified into small vessel disease, such as those involving the eyes, kidneys and nerves (microvascular disease), and large vessel disease involving the heart and blood vessels (macrovascular disease). Diabetes accelerates hardening of the arteries (atherosclerosis) of the larger blood vessels, leading to coronary heart disease (angina or heart attack), strokes, and pain in the lower extremities because of lack of blood supply (claudication).
But, the metabolism compensates. This person starts feeling hungry all the time. Their energy begins to suffer, and they feel cravings for sweet, salty, and fatty foods. This makes it harder for them to comply. But worse than that, depending on their individual response to the law of metabolic compensation, their metabolism has now put on the brakes, slowing their daily calorie burn rate by between 200 and 800 calories per day.

Push-ups would be another example.  We've all seen the classic push-up form deterioration under fatigued conditions: a sagging, excessively arched lower back; forward head posture; and elbows flaring out.  It's the classic "panic mode" strategy employed by beginners.  However, you never see it in experienced lifters; they'll simply fail before the technique breaks down.  Part of this comes from technical proficiency, but it's also related to the fact that the limiting factor shifts from anterior core stability to upper body strength/endurance as an individual gets more experienced.

Though not routinely used any longer, the oral glucose tolerance test (OGTT) is a gold standard for making the diagnosis of type 2 diabetes. It is still commonly used for diagnosing gestational diabetes and in conditions of pre-diabetes, such as polycystic ovary syndrome. With an oral glucose tolerance test, the person fasts overnight (at least eight but not more than 16 hours). Then first, the fasting plasma glucose is tested. After this test, the person receives an oral dose (75 grams) of glucose. There are several methods employed by obstetricians to do this test, but the one described here is standard. Usually, the glucose is in a sweet-tasting liquid that the person drinks. Blood samples are taken at specific intervals to measure the blood glucose.

[Guideline] Whelton PK, Carey RM, Aronow WS, et al. 2017 ACC/AHA/AAPA/ABC/ACPM/AGS/APhA/ASH/ASPC/NMA/PCNA Guideline for the Prevention, Detection, Evaluation, and Management of High Blood Pressure in Adults: A Report of the American College of Cardiology/American Heart Association Task Force on Clinical Practice Guidelines. Hypertension. 2018 Jun. 71(6):e13-e115. [Medline]. [Full Text].