Just briefly I want to mention something for the more savvy readers out there. Many, who are well versed in metabolism, will immediately point out that if you lose weight, then of course you are going to be burning less calories because you have less body tissue. True. But what research shows, and my clinical experience validates, is that the reduced rate of metabolic output goes far beyond what would be predicted from loss of fat mass or muscle mass.
Insulin is vital to patients with type 1 diabetes - they cannot live without a source of exogenous insulin. Without insulin, patients with type 1 diabetes develop severely elevated blood sugar levels. This leads to increased urine glucose, which in turn leads to excessive loss of fluid and electrolytes in the urine. Lack of insulin also causes the inability to store fat and protein along with breakdown of existing fat and protein stores. This dysregulation, results in the process of ketosis and the release of ketones into the blood. Ketones turn the blood acidic, a condition called diabetic ketoacidosis (DKA). Symptoms of diabetic ketoacidosis include nausea, vomiting, and abdominal pain. Without prompt medical treatment, patients with diabetic ketoacidosis can rapidly go into shock, coma, and even death may result.
Again, the answer to why has already been discovered! We have a 24hr clock in our body, known as the circadian rhythm. This rhythm controls what hormones are released and when, it controls our wake sleep rhythm and when working properly signals what physiological processes happen during the day and at night. When you think about it, it is a pretty simple concept that we should be eating during the day and not eating during our biological night. People who are ‘night owls’ often eat during their biological night and it has been shown that the insulin and glucose response to a meal eaten at night is that of a DIABETIC! I was shocked when I first discovered this! This means that even a ‘healthy’ thin person is predisposed to weight gain and gets stuck in fat storage mode if they eat all night long. This is aggravated in people who are predisposed to insulin resistance and metabolic hormone chaos!
The distribution of adipose tissue appears to affect its role in metabolic syndrome. Fat that is visceral or intra-abdominal correlates with inflammation, whereas subcutaneous fat does not. There are a number of potential explanations for this, including experimental observations that omental fat is more resistant to insulin and may result in a higher concentration of toxic free fatty acids in the portal circulation. 
[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].
Aronow WS, Fleg JL, Pepine CJ, Artinian NT, Bakris G, Brown AS, et al. ACCF/AHA 2011 expert consensus document on hypertension in the elderly: a report of the American College of Cardiology Foundation Task Force on Clinical Expert Consensus documents developed in collaboration with the American Academy of Neurology, American Geriatrics Society, American Society for Preventive Cardiology, American Society of Hypertension, American Society of Nephrology, Association of Black Cardiologists, and European Society of Hypertension. J Am Coll Cardiol. 2011 May 17. 57(20):2037-114. [Medline].
Although treatment of sleep apnea with continuous airway positive pressure (CPAP) would logically seem to improve CV outcomes and hypertension, studies evaluating this mode of therapy have been disappointing. A 2016 review of several studies indicated that CPAP either had no effect or a modest BP-lowering effect.  Findings from the SAVE study showed no effect of CPAP therapy on BP above usual care.  It is likely that patients with sleep apnea have other etiologies of hypertension, including obesity, hyperaldosteronism, increased sympathetic drive, and activation of the renin/angiotensin system that contribute to their hypertension. Although CPAP remains an effective therapy for other aspects of sleep apnea, it should not be expected to normalize BP in the majority of patients.
It is common for there to be a development of visceral fat, after which the adipocytes (fat cells) of the visceral fat increase plasma levels of TNF-α and alter levels of a number of other substances (e.g., adiponectin, resistin, and PAI-1). TNF-α has been shown not only to cause the production of inflammatory cytokines, but also possibly to trigger cell signaling by interaction with a TNF-α receptor that may lead to insulin resistance. An experiment with rats fed a diet with 33% sucrose has been proposed as a model for the development of metabolic syndrome. The sucrose first elevated blood levels of triglycerides, which induced visceral fat and ultimately resulted in insulin resistance. The progression from visceral fat to increased TNF-α to insulin resistance has some parallels to human development of metabolic syndrome. The increase in adipose tissue also increases the number of immune cells present within, which play a role in inflammation. Chronic inflammation contributes to an increased risk of hypertension, atherosclerosis and diabetes.
Diabetes is a chronic, metabolic disease characterized by elevated levels of blood glucose (or blood sugar), which leads over time to serious damage to the heart, blood vessels, eyes, kidneys, and nerves. The most common is type 2 diabetes, usually in adults, which occurs when the body becomes resistant to insulin or doesn't make enough insulin. In the past three decades the prevalence of type 2 diabetes has risen dramatically in countries of all income levels. Type 1 diabetes, once known as juvenile diabetes or insulin-dependent diabetes, is a chronic condition in which the pancreas produces little or no insulin by itself. For people living with diabetes, access to affordable treatment, including insulin, is critical to their survival. There is a globally agreed target to halt the rise in diabetes and obesity by 2025.
Metabolic syndrome is increasing in prevalence, paralleling an increasing epidemic of obesity. In the United States, where almost two thirds of the population is overweight or obese, more than one fourth of the population meets diagnostic criteria for metabolic syndrome.  In the United States, data from a 1999-2000 survey showed that the age-adjusted prevalence of metabolic syndrome among adults aged 20 years or older had risen from 27% (data from 1988-1994) to 32%. 
^ O'Gara PT, Kushner FG, Ascheim DD, Casey DE, Chung MK, de Lemos JA, Ettinger SM, Fang JC, Fesmire FM, Franklin BA, Granger CB, Krumholz HM, Linderbaum JA, Morrow DA, Newby LK, Ornato JP, Ou N, Radford MJ, Tamis-Holland JE, Tommaso CL, Tracy CM, Woo YJ, Zhao DX, Anderson JL, Jacobs AK, Halperin JL, Albert NM, Brindis RG, Creager MA, DeMets D, Guyton RA, Hochman JS, Kovacs RJ, Kushner FG, Ohman EM, Stevenson WG, Yancy CW (January 2013). "2013 ACCF/AHA guideline for the management of ST-elevation myocardial infarction: a report of the American College of Cardiology Foundation/American Heart Association Task Force on Practice Guidelines". Circulation. 127 (4): e362–425. doi:10.1161/CIR.0b013e3182742cf6. PMID 23247304.
In the US, 84.1 million adults—more than 1 in 3—have prediabetes, and 90% of them don’t know they have it. Prediabetes is a serious health condition where blood sugar levels are higher than normal, but not high enough yet to be diagnosed as diabetes. Prediabetes increases your risk for type 2 diabetes, heart disease, and stroke. But through the CDC-led National Diabetes Prevention Program, you can learn practical, real-life changes that can cut your risk for developing type 2 diabetes by as much as 58% (71% if you’re 60 or older).