Myths about Exercise, Nutrition & Fitness

- an evidence based approach at MDRF, Chennai, Feb 2014

Dr. Nayanjeet Chaudhury, MD, MPH, Director M&E and Health Services Delivery(NCDs)

Population Services International, India

Certified Personal Trainer (ACSM)

Certified Aerobics Trainer (Reebok)

Exercise Myths !!

If you are not working out till you sweat, you aren’t working out hard enough!!!

• Exogenous heat sweating correlates with raised temp in body tissues, skin and CNS (Hypothalamic influence)

• Endogenous heat (during exercise) Increased metabolic end products intramuscular baroreceptors activated sweating regulation (Mac et al, 1995)

• Sweat rate varies from person to person depending on mean skin temperature and environmental temperature (Nielson, 1965)

Strength training will make you "Bulk up" • Muscle hypertrophy (Increase in

C.S.area depends on the following (Mathias et al, 2007) – Type of muscle fibre acting – Type of muscle action – Phase of muscle contraction

• eccentric vs concentric

– Rest and fatigue of the muscle fibres – Frequency, Intensity, duration and mode

of contraction

• Also important – General nutrition, pre & post work out

meal – Hormonal status (esp. women)

Ab-crunches will lead to a flat tummy ?

• Abdominal weight gain is due to accumulation of

– Subcutaneous fat

– Visceral fat

• Fat loss is more complex. It depends primarily on

– Total calorie expenditure

(which depends on distance covered in walking or running, not on intensity of work)

Ab-crunches will lead to a flat tummy ?

• Six weeks of 7 abdominal exercises, 2 sets X 10 reps, 5 days/wk for 6 weeks No significant effect on body weight, body fat %, abdominal circumference, abdominal/suprailiac skinfold measurements (Vispute et al, 2011)

• Isolated body part exercise no effect on body fat

Ab-crunches will lead to a flat tummy ?

• Combined Aerobic and Resistance Exercise Training decreased abdominal subcutaneous fat and visceral fat (Park, 2003)

• Fat accumulates in dependent parts like abdomen, hence needs extra energy expenditure to hit it.

• Abdominal fat depletion is the last point of the sequence of substrates for fatty acid oxidation

Exercising at lower intensity burns more fat

• The more intense the exercise, the higher is the tendency to – shift substrate utilization from fat to glucose,

– shift from aerobic to anaerobic mechanism.

– once carbohydrate stores are depleted through an intense endurance activity, then fat utilization may happen rapidly.

• High intensity exercise experiments have shown more total fat loss, abdominal and visceral fat loss. (Lee et al, 2012)

Fatty Acid Complement

administered in the body

Diacyl Glycerol and Ceramide

Highly Bioactive and Activates pro inflammatory

pathway

Inhibits Insulin signaling and

promotes fatty acid mediated Insulin

Resistance

Intra Muscular Tri Glyceride

(IMTG)

Innocuous Fatty acid metabolite

Increases Insulin

sensitivity

Recent Studies in Immunology and Bio-signaling

Acute exercise increases triglyceride synthesis in skeletal muscle and prevents fatty acid–induced insulin resistance (S. Schenk and J.F. Horowitz; 2007)

Sedentary

group

Exercise group

Fatty Acid Complement

administered in the body

Diacyl Glycerol and Ceramide

Highly Bioactive and Activates pro inflammatory

pathway

Inhibits Insulin signaling and

promotes fatty acid mediated Insulin

Resistance

Intra Muscular Tri Glyceride

(IMTG)

Innocuous Fatty acid metabolite

Increases Insulin

sensitivity

Recent Studies in Immunology and Bio-signaling

Acute exercise increases triglyceride synthesis in skeletal muscle and prevents fatty acid–induced insulin resistance (S. Schenk and J.F. Horowitz; 2007)

Sedentary

group

Exercise group

Other Exercise myths

An aerobic workout will boost your metabolism for hours, so you can sit and relax the rest of the day

Machines give you a better work out than free weights or body weight

Few nutrition myths

I can eat what I want because my workout will balance my weight off.

Fact 1: Total energy expenditure equals

Basal Metabolic rate

+

Physical Activity(PA) cost

+

Food induced thermogenesis The BMR varies according to sex, age, body size and weight

Fact 2: PA expense depends on Duration of exercise, Body weight & Rate of O2 consumption (ACSM, 2010)

I can eat what I want because my workout will balance my weight off.

Fact 3: an average man loses about 100 kcal on walking for about a mile.

Fact 4: A regular McD Burger 400 kCal

Lose more weight by cutting more calories

• Fact 2: Diet + Exercise leads to greater fat loss than diet alone -Weltman et al,1980 DE 79% vs D 68%

-Zuti & Golding,1976DE 109% vs D 79%

• Fact 3: Add Ex to existing Dieting Amount lost as fat% decreases

(esp. in obese) – Hagan et al,1986

• Men DE, 69% vs D, 70% • WomenDE, 79% vs D, 89%

• Fact 1: Caloric restriction can lead to loss of fat & fat-free mass (Buskirk et al, 1963)

If you are dieting, replace soda with fruit juice

• Ludwig et al, 2001

– baseline intake and changes in soft-drink consumption predicted future weight gain

– Endorsed by several studies later

Body weight during the 10 wk of consuming stable amounts of sugar-sweetened soft drinks or aspartame sweetened soft drinks (Raben et al, 2002)

Meta-analysis of studies relating soft drink consumption to the weighted risk of becoming obese in childhood or adolescence(Malik et al, 2009)

Soft Drinks controversy

If you are dieting, replace soda with fruit juice

• Muraki et al., 2013 (Nurses’ Health Study and Health Professionals Follow-up Study)greater consumption of fruit juice is associated with a higher risk of Diabetes Type II compared to whole fruit.

• Fruit juice has higher G.I. than the whole fruit independent of added sugar

The Fructose hypothesis

Bray, 2013

– Fructose is metabolized in liver

– Increased Fructose intake lipid precursors

lipogenesis and uric acid production

Increased blood lipids, obesity, diabetes, fatty liver, and gout

Table sugar is half fructose !!!

Some other myths

• You should grab a protein shake after workout.

Restrict your carb intake, because carbs lead to weight gain

Bust your myths !

Bibliography • American College of Sports Medicine, Examination Ccertification Review, Edition

3rd. 2010.

• Buskirk ER, Thompson RH, Lutwak L, Whedon GD. Energy balance of obese patients during weight reduction: influence of diet restriction and exercise. Ann NY Acad Sci 1963: 1 10:918-40.

• Hagan RD. Upton SJ, Wong L, Whittman J. The effects of aerobic conditioning and/or caloric restriction in overweight men and women. Med Sci Sports Exerc 1986; 18:87-94.

• Lee et al. Effects of high-intensity exercise training on body composition, abdominal fat loss, and cardiorespiratory fitness in middle-aged Korean females Appl. Physiol. Nutr. Metab. Vol. 37, 2012

• Ludwig DS, Peterson KE, Gortmaker SL. Relation between consumption of sugar-sweetened drinks and childhood obesity: a prospective, observational analysis. Lancet. 2001;357:505–8.

• Mack, G., Nishiyasu, T. & Shi, X. 1995. Baroreceptor modulation of cutaneous vasodilator and sudomotor responses to thermal stress in humans. J Physiol (Lond) 483 (Pt 2), 537– 547.

• Malik VS, Willett WC, Hu FB. Sugar-sweetened beverages and BMI in children and adolescents: reanalyses of a meta-analysis. Am J Clin Nutr. 2009;89:438–9, author reply 439–40.

• Mathias Wernbom, Jesper Augustsson and Roland Thomee. The Influence of Frequency, Intensity, Volume and Mode of Strength Training on Whole Muscle Cross-Sectional Area in Humans´1Sports Med 2007; 37 (3)

• Muraki et al. Fruit consumption and risk of type 2 diabetes: results from three prospective longitudinal cohort studies. BMJ 2013;347:f5001 doi: 10.1136/bmj.f5001

• Nielson, B. and Nielson, M. (1965), On the Regulation of Sweat Secretion in Exercise. Acta Physiologica Scandinavica, 64: 314–322. doi: 10.1111/j.1748-1716.1965.tb04185.x

• Park et al. The Effect of Combined Aerobic and Resistance Exercise Training on Abdominal Fat in Obese Middle-aged Women. J Physiol Anthropol 22 (3): 129–135, 2003

• S. Schenk and J.F. Horowitz; Acute exercise increases triglyceride synthesis in skeletal muscle and prevents fatty acid–induced insulin resistance; The Journal of Clinical Investigation, Volume 117 Number 6 June 2007

• Vispute, SS, Smith, JD, LeCheminant, JD, and Hurley, KS. The effect of abdominal exercise on abdominal fat. J Strength Cond Res 25(9): 2559-2564, 2011

• Weltman A, Matter 5, Stamford BA. Caloric restriction and/or mild exercise: effects on serum lipids and body composition. Am J Clin Nutr l980;33:1002-9.

• Zuti WB, Golding LL. Comparing diet and exercise as weight reduction tools. Phys Sportsmed l976;4:49-53.