Lecture 8 - Obesity, Metabolic Syndrome, Dyslipidaemia Flashcards
What is Obesity?
It’s an excess of body fat frequently resulting in a significant impairment in health.
Ways to measure overweight and obesity:
Height and weight tables:
-considered obese if >20% above desired weight listed
BMI [for adults]
- overweight <25 kg/m2
- preobese 25< BMI <29.99 kg/m2
- Grade 1 obesity: 30< BMI < 34.99 kg/m2
- Grade 2 obesity: 35 < BMI <39.99 kg/m2
- Grade 3 obesity: >40kg/m2
Waist Girth:
-Significant risks at WG >102cm for men and WG > 88cm for women.
Waist to Hip Ratio:
- Significant risks at WHR >0.8 for women and >0.9 for men.
Phenotype:
- Type I = Excess body mass or %fat
- Type II = Excess subcutaneous truncal-abdominal fat [android]
- Type III = Excess abdominal visceral fat
- Type IV = Excess gluteal-femoral fat [gynoid]
Body fat percentage:
- Significant risks at >25% fat for men and >35% fat for women
- Skin folds
- Hydrostatic weighing
- DEXA
What influences predispose individuals to obesity?
BEHAVIOURAL:
- socioeconomic status [education]
- activity level
- nutrition
METABOLIC:
- genetic factors
- metabolic and endocrine factors
BIOLOGICAL:
- Race
- Gender
- Age
- Pregnancy
CULTURAL/SOCIETAL:
- Media
- Work Practices
- Transport
- Urbanisation/modernisation
Drugs for Treating Obesity:
- Phentermine [ Adipex-P, Lonamin]
Current weight loss are appropriately recommended for individuals with a BMI >30 or with a BMI>27 if they have obesity relate comorbidities
is recommended for short term use - Acts as an appetite suppressant but causes dry mouth, palpitations, and anxiety
Drugs for Treating Obesity:
- Lorcaserin [Belviq]
It’s a serotonin receptor agonist: reduces appetite
Given in addition to lifestyle modifications, lose about 2-3kg more than placebo over the course of a year
Side effects: headaches, dizziness, fatigue, nausea, dry mouth and constipation. Rare chemical imbalance [serotonin syndrome], suicidal thoughts, psychiatric problems.
Drugs for treating obesity:
- Orlistat [Xenical, Alli]
It’s a pancreatic lipase inhibitor: blocks the digestion and absorption of fat in your stomach and intestines.
It decreases fat absorption by 30% = further increase of dietary fat [leakage!!!] - excess fat is release through oily diarrhoea.
Phentermine and Topiramate [Qsymia] [appetite suppresant] = capable of 12% to 14% weight loss
Health Benefits of a 10% Weight loss:
BP : decline of about 10mmHg is systolic and diastolic BP in patients with hypertension equivalent to that with most BP medication
Diabetes:
Decline of up to 50% in fasting glucose for newly diagnosed patients
Prediabetes:
>30% decline in fasting or 2h post glucose insulin level >30% increase in insulin sensitivity, 40-60% decline in the incidence of diabetes
Lipids: 10% decline in TC 15% decline in LDL chol 30% decline in TRIG 8% increase in HDL chol
Mortality:
>20% decline in all cause mortality
> 30% decline in deaths related to diabetes
>40% decline in deaths related to obesity
ACSM Guidelines:
Prevent gain weight:
- 150-250min/week of mod int PA is associated with prevention
- more than 150min/w of mod int PA is associated with modest weight loss
Weight loss:
- 150 -250min/week only provides modest weight loss
- greater amount [>250] provide clinically significant weight loss
For weight maintenance after weight loss:
- there’s some evidence that >250min/week will prevent weight re-gain
Exercise prescription:
Both cardiorespiratory + resistance
Frequency:4-5 days/week
Duration: 40-60min
Intensity: 50-60% VO2max
RT may not enhance weight loss but may increase/maintain fat free mass and is associated with reductions in health risk
Safety concerns during PA for obesity:
- Musculoskeletal screening recommended for obese clients
- 12 lead ECG
- BP response
- Signs of dyspnoea
- Signs of metabolic disturbances [hypoglycaemia] - BGL’s
Considerations to make when developing physical activity programmes for the severely obese:
Barriers:
- Physical, psychological, economic, an programme based
Safety issues:
- co morbid medical conditions
PA options:
- low intensity activity [gardening]; non-weight bearing activity [swimming, water aerobics]; walking [increases caloric expenditure]
Programme goals:
-caloric expenditure and weight loss [300-500kcal/session and 2000 kcal/week], QOL, improved mood, improved physical conditioning
Promoting adherence:
- develop good rapport, patient eduction, address barriers, provide progressive feedback, use prompts and rewards, develop social support.
Management of Metabolic syndrome:
If focus is on obesity as underlying cause - prevent and treat obesity
If focus is on insulin resistance as underlying cause - treat insulin resistance and prevent T2D
If focus is on individual risk factors - treat individual risk factors, such as: Low HDL chol, high Total C
Hoes does exercise help:
Well as MetS is a clustering of risk factors, exercise helps by reducing/preventing/treating each of them
Exercise is the only therapy that can do so
Lipids
A study exercised 13 men with hyperlipidaemia and 12 men with normal lipids on a treadmill at 70% of peak VO2max. They exhibited a significant decrease in TRIG
A single bout of exercise can increase TRIG removal at the next meal.
Aerobic exercise that’s at least moderate intensity 3x/week can
- increase HDL-C
- Reduce total chol, LDL & TRIG
Lowering blood cholesterol:
Primary focus of diet therapy is on lowering LDL-C:
- high saturated fat intake and high dietary chol reduce LDL clearance
- diets high in polyunsaturated fat may reduce HDL levels
- high carbohydrate diets may reduce HDL levels and raise TRIG’s
- monounsaturated fats apparel to lower Total- C and possibly increase HDL levels
- fibre sequesters bile and can reduce LDL levels by 5-10%
Lowering blood cholesterol:
Advise adults who would benefit from LDL-C lowering to:
Consume a dietary pattern that emphasises intake of vegetables, fruits and whole grains; includes low-fat dairy products, poultry, fish, legumes, no tropical vegetable oils, and nuts, and limits intake of sweets, sugar-sweetened beverages and red meats
Adapt this dietary pattern to appropriate calorie requirements, personal and cultural food preferences, and nutrition therapy for other medical conditions
Reduce % of calories from saturated fat
Reduce % of calories from trans fat
Metabolic Syndrome
MetS predicts development of both diabetes and CVD.
Insulin resistance and obesity characterise most individual subjects with the MetS
Initial therapy for the MetS should consist of diet modification and increased PA
Some of the conditions associated with MetS include obesity, high BP, dyslipidaemia and insulin resistance
Glucose
Muscle contraction moves glucose into the cell via glut-4, independent of insulin
Glucose oxidation during exercise:
- muscle contraction-mediated glucose uptake [non-insulin]
- increased metabolic rate and fat oxidation
Insulin sensitive effects:
-postprandial
Hypertension:
Acute endurance training session [1 session] can have a significant reduction in BP [~6mmHg] up to 24 hrs
Chronic endurance training significant reductions in BP however no real reductions after 10 weeks
Besides the metabolic and endocrine changes, there’s a mechanical adaptation :
- Left ventricular hypertrophy [LVH]
=hypertension causes LVH, endurance exercise training decreases LV mass [~12%]
Hypertension & Endurance training:
Endurance training produce an almost immediate decrease [1-2weeks] of 5-7mmHg in bot SBP and DBP independent if weight loss
Reduces stroke and CAD risk by 30%
RT produces a lesser decrease of 3mmHg
Avoid intense exercise [aerobic & resistance] in patients with BP >180/85mmHg
Hypertension : Mechanism for decrease in BP
Reduction on NE secretion
Increase in endothelia-derived nitric oxide due to sheer stress on blood vessel wall and vasodilation
Arterial stiffness is related to hypertension and CAD:
- can be assessed by pulse wave analysis using pressure transducer on the brachial artery
- endurance training [2-3h/wk] reduces arterial stiffness by 30%, without change in BP
Drugs for treating MetS:
Antihypertensives:
- ACE inhibitors and ACE receptor inhibitors [Cato-ren, coversyl, avopro, tritace, atacand, micardis, karvea] = inhibits angiotensin converting enzyme action to reduce blood vol and reduces Vasoconstriction
~ Exercise consid= ACE do not affect exercise HR or exercise tolerance
- Betablockers = BB receptors on cardiac muscle to reduce HR and hence BP
=reduces resting and exercise HR in a dose-dependent basis
~exercise consid= cant use HR as guide to exercise intensity - Vasodilators = increases capacity of vascular system to lower BP
~ susceptible to fainting after exercise - Diuretics = action on kidney tubules to reduce reabsorption of sodium and increase potassium excretion
=requires potassium replacement
~ causes cardiac arrhythmias
-Calcium Channel Blockers = reduce HR [negative chronotropic effect], reduces contraction to of cardiac muscle and vascular smooth muscle [negative ionotropic effect] and increases vasodilation
~cant use HR as guide to exercise intensity
Hypolipemic Agents:
- Statins = inhibitor of HMG CoA Reductase, thus reducing hepatic synthesis of chol
=reduces TC, LDL by 30-35% and increases HDL by 5-15%
~adverse reactions - 10-25% of patients on high dose statin meds
Hypoglycemic Agents:
- Metformin= med of choice for T2D and obesity
=increases insulin sensitivity
- Sulphonureas = increases insulin secretion but may also cause weight gain
Insulin preparations:
- short acting insulins = Actarapid [peak 3h lasts 8h], humalog [peak 1h lasts 4h]
- longer acting insulin’s = protophana [peak 12h lasts 12-24h], lantus [last 24h]
Describe Dyslipidaemia:
Abnormal blood lipids - can contribute to the development of atherosclerosis, a build up of fatty deposits in the blood vessels which may lead to the development of CV diseases
Dyslipidaemia is a risk factor for chronic disease such as CHD and stroke
Drug therapy for Dyslipidaemia :
Statins:
- reduce Total C 15-30%, lower LDL 20-40%
- inhibits chol production in the liver and increase LDL receptors number in the hepatic and other tissues
- LDL lowering with statins can decrease rate of heart attaCks and deaths form CHD ~30%
- Effective in persons with or without CHD
- can cause hepatotoxicity and myopathy [<1%]
- contraindications: chronic liver disease, pregnancy
Nicotinic Acid [or niacin]:
- lowering VLDL production and raises HDL
- decrease HDL clearance = elevated HDL
- can cause skin irritation and flushing, liver toxicity, hepatic failure
- not recommended for individuals with hypotension
Fibric acid derivatives:
- increase LPL activity - increase TRIG hydrolysis, and increased HDL 10-15%
- also reduce fatty acid uptake by the liver = thereby slowing hepatic TRIG synthesis and VLDL production
- side effects = GI distress, gallstones, myopathy
Probucol:
- inhibits LDL oxidation = reduced risk of atherosclerosis
- reported to decrease HDL, prolong QT interval on ECG
Bile acid sequestrate:
- promotes chol elimination through the digestive tract by binding bile acids in the intestines
- lower LDL and can be used alone or in combination with statin drugs
- can cause gastric irritability, increase TRIG levels and constipation
- interferes with absorption of warfarin, digoxin, and thyroxine
Graded exercise testing:
Atherogenic blood profile is not a contraindication for exercise
But its a risk factor for CAD
Therefore must examine signs and symptoms of CAD
Hyperlipidaemia : Exercise Testing
METHODS:
Aerobic:
- Cycle [ramp protocol 17 watts/min, staged protocol 25-50watts/ 3min stage]
- Treadmill [ 1-2METs/3min stage]
MEASURES:
- 12 lead ECG, HR
- BP, rate pressure product
- RPE [6-20]
ENDPOINTS: ~ VO2peak/ work rate ~ serious dysrhythmias ~ >2mm ST segment depression or elevation ~ ischemic threshold ~ T wave inversion with significant ST change ~ SBP >250mmHG, DBP >115mmHg ~ Exaggerated or hypotensive response ~ volitional fatigue
METHOD
Endurance:
- 6min walk
MEASURE
-Distance
ENDPOINTS
- note time, distance, symptoms at rest stops
Exercise Programming:
Minimum amount of exercise needed to improve blood lipids not known
A dose-response relationship between volume of PA and HDL has been identified
MODE:
- RT doesn’t seem to alter fasting serum lipid and lipoprotein level, but data is limited
- Aerobic training lower TRIG and elevates HDL
FREQUENCY:
- HDL elevated 18-24h post exercise for 48-2h
- <3 sessions per week
INTENSITY:
- Improvements in lipid profile observed with exercise at 50-60% HRmax
DURATION:
- optimal duration not known
- 45-60min is recommended
