The Science of Weight Loss
At a physiological level, weight loss and weight gain revolve around caloric consumption and expenditure. Because of this, it's important to understand the basics of calories. Put simply: we lose weight when we eat less calories than we expend. Conversely, we gain weight when we eat more calories than we expend. In order to lose one pound of fat, we must create a 3,500 calorie deficit, which can be achieved either through exercise or diet.
DIETING AND MECHANISMS OF WEIGHT LOSS
3 Groups – One Consistent Finding
95% of all dieters regain their lost weight within one to five years
Several long-term follow-up studies have shown that the success rate of diets, over time, is dismal at best. It is estimated that 95% of diets simply don’t work over the long term
Studies have shown that 90-95% of individuals who diet are unsuccessful in the long term
Why don’t diets work?
They focus on short term results (vs long term, permanent weight loss)
They focus on reducing calories as the priority (often at the expense of good nutritional principles)
They often change the ratio of fat to muscle mass negatively (which leads to further weight gain)
Mechanism of weight loss
Quite simply, to lose weight a person needs to consume less calories than they use OR use more calories than they consume
Diet programs focus on reducing calories consumed
Exercise programs focus on increasing calories used
Diet and exercise combined will obviously provide the quickest weight loss results
Metabolism and Metabolic rate
Metabolism
The chemical processes occurring within a living cell or organism that are necessary for the maintenance of life
Metabolic Rate
The rate at which your body burns calories performing normal everyday activities (neither gaining weight nor losing weight)
TDEE and BMR
Total Daily Energy Expenditure (TDEE)
70% calories required for BMR
15% calories required for exercise
15% calories required for food digestion
Basal Metabolic rate (BMR)
Minimum calorific requirement needed to sustain life in a resting individual
BMR responsible for approximately 70% of all calories burned in a single day
BMR and Calories
The effects of exercise on BMR
Resistance training and BMR
Resting lean muscle mass accounts for 80% of BMR
Therefore increasing a person’s lean muscle mass (through high intensity resistance training) would increase their BMR
CV training and BMR
Aerobic fitness contributes towards BMR
Therefore increasing a person’s level of fitness (through high intensity CV training) would increase their BMR
BMR IN RESPONSE TO EXERCISE
Lower intensity activity burns slightly more fat calories than high intensity
Metabolic rate remains elevated for some time after both activities (thereby continuing to burn CHO and fat calories at a greater rate when at rest)
Metabolic rate remains elevated longer after high intensity activity
High intensity activity brings about permanent increase in BMR
BECOME A FAT BURNING MACHINE
SUMMARY – Factors affecting BMR
Factors affecting BMR are:
Lean muscle mass
CV fitness
These are brought about through:
Resistance training
High intensity CV training
The result is a permanent increase in BMR
As long as fitness levels are maintained
SUMMARY – Factors affecting weight loss
Factors affecting fat loss are:
Structured bouts of activity
These are brought about through
Long duration CV training
Frequent bouts of Activities of Daily Living (ADL)
These activities do not bring about any permanent changes in BMR
NUTRITION AND WEIGHT LOSS
Energy Intake
If successful weight loss is about energy balance it is equally important to consider energy intake
The only nutrients that contain energy are carbohydrates, fats and protein (these are called macro-nutrients). Alcohol contains energy but is not a nutrient!
The role of fats in fat loss
When someone goes on a diet (minimising fat intake) the body holds onto its fat stores in response
Thus someone on a low fat diet may lose weight but it is likely to be muscle not fat
Fat (good fats) must be consumed to lose fat
Some low fat products have additional and high levels of sugar causing insulin release
Common nutrition problems
Most people present in one or two categories:
They consume too much fat and processed foods
They consume a low fat diet but one high in carbohydrates
So what should we do?
Minimise fat intake
Mediate carbohydrate ingestion
Or both
You should also ensure protein intake is optimal:
Maximises recovery
Helps you feel full
Will not be stored as fat*
*When consumed in slightly higher quantities than normal for a relatively short period
Excessive Carbohydrate (CHO) consumption can exceed storage limit and therefore store as fat.
Insulin resistance means more insulin and less glucagon to facilitate fat metabolism.
We become a carbohydrate burning machine.
To assist with weight loss we need to become a fat burning machine.
Consuming enough ‘good fats’ (we need to eat fat to lose fat), reducing CHO intake (reducing insulin) and ensuring enough protein (doesn’t store as fat) is present shifts the emphasis towards fat burning.
A multivitamin and range of multivitamin rich foods supports the process.
Stay hydrated as activity levels will change water requirements.
Glucose
Gives a body energy, helps with self-repair and growth, and performs cellular tasks
Delivered to the muscle by insulin
Muscle is like a ‘fuel tank’
When it is full, excess glucose (glycogen) goes to our fat stores instead of muscles
Amino Acids
The building blocks of proteins and essential to nearly every bodily function. Every chemical reaction that takes place in your body depends on them
Delivered to the muscle by insulin
Body takes what it needs and gets rid of the rest
Fatty Acids
Produced when fats are broken down. Can be used for energy by most types of cells. They also move oxygen through the blood stream and aid cell membrane development, strength and function
Goes straight to fat stores
Must have good fats in diet to burn fat
Used for energy when muscle glucose levels are low
Insulin
Release in the response to the presence of glucose in the blood
Needed to transport glucose and amino acids into the muscle
Distributed in excessive amounts to reduce excessively abnormal blood sugar (high carbohydrate diet)
High levels of insulin may contribute to our fatness
Cells can become resistant to insulin turning our bodies into carbohydrate burning machines
Glucagon
Works with insulin to control blood sugar
Mobilises stored energy (either glycogen or fats) into the bloodstream available for use
Glucagon required to burn fat (fat burning friend)
High levels of insulin limit glucagon
Monitor carbohydrate levels in diet in order to promote fat burning
Micronutrients
Ensure system operates at maximum efficiency
Alcohol
Goes straight to the muscle
Used in preference to glucose in the bloodstream and glycogen and fat stores
Food eaten while consuming alcohol is diverted to fat stores
GUIDELINES FOR DAILY INTAKE
HORMONES
Insulin
Released in the presence of glucose in the blood
Needed to transport glucose and amino acids into the muscle
Distributed in excessive amounts to reduce abnormally high blood sugar (high carbohydrate diet)
High levels of insulin may contribute towards our fatness
Cells can become resistant to insulin turning our bodies into carbohydrate burning machines
Glucagon
Works with insulin to control blood sugar
Mobilises stored energy (either glycogen or fats) into the bloodstream available for use
Glucagon required to burn fat (fat burning friend)
High levels of insulin limit glucagon
Monitor carbohydrate levels in diet in order to promote fat burning
Cortisol
Stress hormone
High insulin increases secretion
High cortisol associated with a drop in testosterone and Human Growth Hormone (HGH)
Also activates fat cells to store fat
Leptin
Tells the body when to eat and when we are satisfied
Produced by body fat
Some people can develop resistance to leptin causing an increased desire to keep eating and/or cravings
Serotonin
Signals satisfaction
Low levels cause depressions, obesity and lethargy
Also can cause a preference for refined carbohydrates and overeating because the brain senses it is starving
Protein restrictive diets cause serotonin levels to plummet
Thyroid
Regulates the metabolism
Low thyroid (hyperthyroidism) affects approximately 30% of the population
Low thyroid reduces our fat burning rate and inhibits energy levels
Hormones in Summary
Excessive production of Insulin is a problem
Caused by high carbohydrate consumption – particularly high GI
Testoserone and HGH produced during resistance training maximise fat loss
Resistance training helps to tip our hormone balance in favour of weight loss
Regular exercise also reduces stress thereby keeping Cortisol at bay and improving Serotonin levels
A TALE OF TWO TWINS
Both weigh 90kg and are 40% body fat
TWIN A DECIDES TO LOSE WEIGHT ON A DIET
TWIN B CHOOSES EXERCISE AND DIET
After 10 weeks both lose weight
TWIN A LOSES 20KG PAYING FOR PRE-PACKAGED MEALS
NOW 70KG JUST 10 WEEKS LATER
TWIN B IS FRUSTRATED SHE HAS ONLY LOST 10KG
NOW 80 KG IN 10 WEEKS
After 10 weeks both change body composition
TWIN A IS NOW 35% BODY FAT
40% OF 90KG = 36KG FAT
35% OF 70KG = 24.5KG FAT
<11.5KG FAT
TWIN B IS NOW 30% BODY FAT
40% OF 90KG =36KG FAT
30% OF 80KG = 24KG FAT
<12KG FAT
Results are very different
BACK TO NORMAL
LOST 20KG FAT BUT ONLY 11.5KG FAT
LOST 8.5KG OF MUSCLE / LEAN BODY MASS
<METABOLISM
REDUCED EXERCISE
LOST 10KG OF WEIGHT AND 12 KG FAT
GAINED 2KG LEAN / MUSCLE
>METABOLISM
10 WEEKS LATER
BACK TO 90KG BUT WITH 8.5KG LESS LEAN MUSCLE MASS
8.5KG FATTER
DOWN TO 70KG AND
INCREASED METABOLISM
(INCREASED FAT LOSS)
LEANER
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