1 Exercise, Fitness and Weight Loss
2 Calories In vs Calories Out Calorie Theory of Weight Loss Perpetuates the idea that people who are overweight eat too much and move too little i.e. either sloths or gluttons Is concept drives the idea that the more exercise you do, the slimmer you’ll be Marathon runners? Change our perspective!
3 Calories In vs Calories Out The body is more like a thermostat than a scale You reduce your calories in and it does two significant things: 1. Increases your hunger via the hypothalamus 2. Makes you tired to reduce your energy expenditure You expend lots of calories through exercise your body does some significant things: 1. Makes you more efficient at utilising stored fat (i.e. you end up using less for the same exertion) 2. You do less incidental exercise 3. Increases your appetite to replace lost energy
4 Exercise Most people think that exercise is the primary driver of weight loss (this is not an evidence based idea) Weight loss is driven by our diet/food (hormones) and exercise can compliment this Specific exercise strategies will aid weight loss and improve a number of health markers Why does exercise not drive weight loss?
5 Energy Expenditure 1. Basal Metabolic Rate - The amount of energy the body needs at rest, on a day to day basis to stay alive - Nothing to do with movement or digestion 2. Movement - All physical activity including exercise, spontaneous movement and incidental exercise 3. Thermic Effect of Food - The energy required to metabolise (breakdown) food
6 Energy Expenditure 1. Basal Metabolic Rate = ~60-70% - Exercise can increase BMR particularly weight training and increase CV fitness 2. Movement = ~20-30% - Maximised through a physical active lifestyle 3. Thermic Effect of Food = ~10% - Maximised by eating an unprocessed diet
7 Vicious Cycle EAT LESS CALORIES LOSE WEIGHT DECREASED ENERGY EXPENDITURE INCREASED HUNGER REGAIN WEIGHT
8 What Does the Research Say? Over the last 35 years of looking at semi-starvation diets (i.e. reduced calories), they are all very similar in their failures Dr Jason Fung: “A perfect 35 year record unblemished by success” Research published in the Journal of Sports Medicine (1989) where scientists trained sedentary subjects to run a marathon over 18 months – men had average weight loss of 5 pounds and women had no weight loss AND no change in body composition was observed
9 What Does the Research Say? A 10 year study looked at a “normal diet cohort” vs “eat less and exercise more cohort” and after 10 years there was 1kg difference between the two groups Another 12 month RCT by McTiernan et. al. looked at 102 men and 100 women – participants did 6 x 1 hour of moderate – vigorous exercise every week. Men lost 1.8 kg and the women lost 1.4kg (women started at 78kg and the men at 96kg)
10 The Overeating Paradox Studied convicts at Vermont State Prison (Dr Ethan Sims) Increased calorie intake to 4000 calories/day – gained weight but then it stabilised Continued to increase calories up to 10000 per day while carefully controlling exercise It took 4-6 months to increase weight by 20-25% (one man had less than 10 pounds of weight gain) Metabolism increased by 50% After the study the participants very rapidly lost the weight they had gained It seems that it’s not calories that are driving weight gain or weight loss The body has it’s own set point and it will try to always go back to that point – therefore it is not the overfeeding that causes the weight gain but messing up the set point
11 Hormonal Theory of Weight Loss The theory that the macronutrient content of food is far more important the estimated caloric content The macronutrient content influences the the hormones that our body produces Therefore, hormones are the driving force behind weight gain and weight loss This makes sense as it is our neuroendocrine system that regulates appetite Refined carbohydrate, especially grains and fructose, have an ability to disrupt the neuroendocrine system
12 Exercise as a Drug Exercise is the most potent “drug” in the world Getting the dose right though is important Dose is based on the individual There is significant research emerging that we can obtain significant health benefits at much smaller volumes Our body adapts very early on in training One study concluded “3 min of all-out exercise performed within a 30 min time commitment per week including warm-up and cool-down, improved skeletal muscle oxidative capacity and indices of cardiometabolic health including VO 2 peak and blood pressure, in overweight/obese adults.” (Gillen et. al., 2014)Gillen et. al., 2014
13 So What Should I do? It depends The focus should be on improving all aspects of fitness i.e. both cardiovascular fitness and muscular fitness Muscular fitness increases BMR (to varying degrees) and improves the function of all systems of the body Improving cardiovascular fitness can literally save your life
14 Number 1 Risk Factor for any Cause of Death Low cardiovascular fitness was found to be the number 1 risk factor for all-cause mortality (any cause of death) Hypertension was a very close second Barry et. al. (2014) found that when an obese or overweight individual was fit their relative risk for any cause of death was almost identical to those of a normal weight-fit individual (1.1 compared with 1.0) Barry et. al This indicates that the primary health intervention should be on improving cardiovascular fitness NOT weight loss Improving fitness will improve health whereas not all weight loss is healthy
15 Cardiovascular Fitness and Relative Risk for All-Cause Mortality BMI and FitnessRelative Risk Normal weight and fit1.0 Normal weight and unfit2.2 Overweight and fit1.1 Overweight and unfit2.5 Obese and fit1.1 Obese and unfit3.2
16 Exercise Prescription High intensity exercise should be incorporated into a program with low intensity on alternate days If you go high intensity then the duration is short Time can be anywhere from 5 minutes for a beginner through to an hour for an athlete Beginners can do 10-15 minutes of high intensity exercise 1-2 times a week Intensity is based on heart rate calculations or percentage of 1 repetition maximum (1RM) HIIT is approximately 85-95% of heart rate reserve (HRR) Sprint training is >100% of HRR Weight training should aimed at heavier weight and less reps Full recovery is required before the next session (i.e. no soreness/DOMS)
17 Exercise Prescription Why high intensity? The body does not adapt unless you reach your training threshold Training threshold is simply the minimum stimulus your body needs to adapt When we train, we damage the cells of body which forces an adaptation (change) The greater the damage the greater the adaption (to a point – there is a dose- response relationship) Life saving cardiovascular adaptations occur when we train the CV system and this can occur rapidly with high intensity, short duration exercise Our muscles recruit small fibres before big fibres (size principle) and will only recruit our powerful muscles when there is appropriate stimulus (i.e. load) In this way, intensity is king
18 Intensity Intensity can be manipulated in many ways: Increasing weight Increasing speed (i.e. sprint or plyometrics) Decreasing speed (increasing time under tension) Destabilising Unilateral training Isometric holds (contraindicated in people with high blood pressure) Pulse and matrix training Increasing the volume or length of training Increasing the complexity of the training Reducing rest times
19 So How Much? It comes down to the individual Focus on improving cardiovascular and muscular fitness Don’t be afraid of high intensity training You may choose to alternate between high and low intensity training Allow for full recovery between sessions (this is critical and will affect your results if not done properly) You don’t need to train for hours I do 15 minute strength training workouts and 20 minute runs I do this because I enjoy it. What do you enjoy? What are you most likely to stick to? The best results come from a personalised program. You should see an exercise physiologist, personal trainer or you can book an appointment with me (Skype or contact)