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

  1. Lower intensity activity burns slightly more fat calories than high intensity

  2. 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)

  3. Metabolic rate remains elevated longer after high intensity activity

  4. 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:

  1. They consume too much fat and processed foods

  2. 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

  1. Excessive Carbohydrate (CHO) consumption can exceed storage limit and therefore store as fat.

  2. Insulin resistance means more insulin and less glucagon to facilitate fat metabolism.

  3. We become a carbohydrate burning machine.

  4. To assist with weight loss we need to become a fat burning machine.

  5. 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.

  6. A multivitamin and range of multivitamin rich foods supports the process.

  7. 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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