Because the times of day and night that we eat affect our body’s circadian clock rhythm, which regulates all aspects of metabolism, meal timing can have serious implications for the development of cardiovascular disease (CVD), type 2 diabetes, and obesity.
The body is in a fasted state after about 12-14 hours of sleep. This will have the following impact on the body:
- CHO reserves will be depleted.
- Fat mobilization is slowed down.
- The muscle will be in a mild catabolic state.
The aim of breakfast is to rev-up the metabolism and fat burning within the body and to replenish glycogen stores within the muscle and liver. Breakfast is the most important meal of the day and should be consumed within 30-minutes of waking up. The nutrient composition should be high in complex carbs, a fast acting protein providing essential amino acids and a portion of essential fatty acids such as flax seeds or walnuts.
After the breakfast, blood sugars will start to dip and a client may start to feel hungry. The mid-morning snack should be eaten two hours after breakfast, and its main aim is to balance out the blood sugars, stop the client from feeling hungry and to keep their metabolism burning through till lunch. The snack should have a portion of low glycemic CHOs and a portion of casein protein.
Lunch should be consumed two to three hours after the mid-morning snack and should be the second largest meal of the day. At this point during the day, a client’s body should be well balanced and in a state of equilibrium. The aim of lunch is to sustain the energy required for the afternoon, to maintain level blood sugars and to keep the body’s metabolism fired up. Encourage the client to add a portion of protein such as fish, chicken, whey or egg along with a portion of low glycemic carbs. If they eat fish then they will be getting a good intake of essential free fatty acids. If not, suggest adding some nuts like walnuts.
It is very common for your client to feel a post-lunch dip in energy; this may be attributed to an insulin rebound effect caused by eating lunch and their muscles being in a mild catabolic state. The aim of this snack is to ease up the blood sugar levels and the focus should be on carbs and proteins; to get energy levels back on track. One suggestion could be a nutrition bar that is low in sugar combined with a casein protein shake because of its slow releasing amino acids. It isn’t desired for a client to dump sugar into their body, although they may be tempted. This will only confuse their metabolism and a crash of energy will be on the horizon before dinner. A steady approach and keeping the body in equilibrium will aid in burning calories and weight loss.
This is the last main meal before a client will go to sleep and should be consumed within 4 hours after their lunch and within two hours after the afternoon snack. The main focus of this meal is again to keep the metabolism high with low carbs, high protein, and moderate fat meal composition. The carbs should be fiber rich and low in sugar, with casein-rich protein and some essential fatty acids from canola oils, nuts and seeds.
This is a light snack two hours before your client goes to sleep and should be low in carbs, high in protein and essential fatty acids. This snack should enable their body to use fat for energy, keeping their metabolism still burning and to reduce the usage of muscle glycogen and protein during the later stages of sleep.
The Role of Intermittent Fasting during the Cutting Phase
Intermittent fasting is another approach that can be used with a client, instead of the conventional 5 or 6 small meals per day.
Be aware that intermittent fasting is not the magic bullet to weight loss but is another strategy that can be discussed and implemented with a client.
Intermittent fasting (IF) is the time from eating the last food intake until eating the next meal. This break is termed a ‘fast’ and can be interrupted by sleep or by the designated time of the fast. A simple example of an IF is the 12/12 model where dinner is eaten at 7 pm and fast or sleep until 7 am breakfast time. This 12/12 fast maybe the norm for some people as it mirrors their sleep and eating patterns. This is one of the additional bonuses of IF is that it can be adjusted to suit the needs of every individual in terms of time and lifestyle. Therefore, IF is not a diet, it is a pattern of eating and it is a method of organizing meals so that one can get the most out of them.
Some individuals cut calories and others try to keep the calories consistent to start off with and to change the timing of the meals to suit their lifestyles. Some people eat larger meals in a smaller timeframe and this method of eating is excellent for keeping muscle mass while trying to get lean. However, the main purpose of IF is to reduce the % body fat and requires very little behavior modification in comparison to the ‘fad diets’. From a lifestyle perspective, it is simple enough to sustain and meaningful enough to implement change.
What are the Main Mechanisms behind Intermittent Fasting?
Firstly, to understand the mechanism behind intermittent fasting, the difference between the fed state and the fasted state needs to be established. A body is in the fed state when it is performing digestion and absorption of the foods consumed and this usually lasts for about 3-5 hours. When a body is in a fed state, it is very hard work to burn fat because the insulin is high to help regulate blood glucose. After this timespan the body goes into a phase known as the postabsorptive state; and this lasts for between 8-12 hours after eating the last meal, which is when a body enters into a fasting state. During this fasting state, it is much easier to burn fat because the insulin levels are low.
Due to the key fact, we don’t enter into a fasted state until roughly 12 hours after our last meal; it is unusual for our bodies to be in this burning fat state. Hence, the inaccessible fat is burnt within the body, and due to this burning fat state which is rarely seen in normal eating schedules, many individuals lose weight without reducing calories, the amount of food consumed or the impact of exercise. The key to this mechanism is the timing (e.g. 12-14 hours after eating and getting into a fasting routine that suits your lifestyle).
Research has also shown that intermittent fasting enhances the effectiveness of insulin to store glucose and is used to breakdown fats, this mechanism is called ‘insulin sensitivity’. An increase in ‘insulin sensitivity’ is related to weight gain, diabetes, obesity, CHD and PVD.
Ketones are a by-product of burning fat and intermittent fasting also affects brain function by boosting the production of a protein called brain-derived neurotrophic factor (BDNF). Fasting on alternate days (restricting meals on fasting days to about 600 calories) can boost BDNF levels from 55 to 450%, and BDNF is essential for the following reasons:
- It protects the neuro-motor from degradation within the muscular system.
- The BDNF is the major neuromotor catalyst within the neuromuscular system required to fire the muscle into action.
- BDNF is involved within the brain and muscle; this is a major rationale behind high-intensity exercise with IF for improving brain tissue.
- BDNF is associated with a reduction of cellular inflammation and free radical damage.
Practical Benefits of the IF Plan
- IF is easy, then breakfast needn’t be prepared. All that is needed is a glass of water.
- By skipping meals, money is saved and time in the kitchen preparing food.
- IF is easy to follow, and getting over the first hurdle will help one move away from the fact that eating all the time is not necessary.
Intermittent Fasting and Weight Loss
When insulin levels are high after eating, it stops the metabolism of fat by inhibiting the release of glucagon. When insulin levels are reduced after fasting, glucagon levels are high and fat metabolism is increased.
One small human study in the American Journal of Clinical Nutrition highlighted that alternate day fasting in a sample of 16 subjects had a significant impact on weight loss after 16 weeks. The study results indicated that each of the subjects had a healthy weight loss of 3% from their baseline weight and a 4% reduction in fat mass. These results indicated that the research subject didn’t consume two days worth of calories on feeding days to make up for calories lost on the fasting days.
Intermittent Fasting and Muscle Gain
Most bodybuilders tend to use a 12-16 hour fasting model for increased muscle mass. Research has indicated that 50% of the muscle amino acids (AA) were responsible for glucose maintenance post 16 hours and were using 100% muscle AAs at the 28-hour mark. Before, going any further, the primary mechanism for glucose utilization needs to be discussed as follows:
- The primary source of glucose within the body is carbohydrates, but the body can make glucose by breaking down the amino acids and glycerol within the body. This mechanism is called gluconeogenesis.
- Glucose/glycogen is stored in the muscle and liver respectively and can be broken down quickly to meet the energy demands of the body and released into the bloodstream.
In a fasted state the body is no longer absorbing nutrients from the last meal but is relying on three sources – the glycogen stores within the muscle and liver, body fat which is broken down into free fatty acids and glycerol which is converted to energy. It should be noted that the liver glycogen will run out after about 16 hours (this depends on BMR, age, activity levels, fitness levels etc). The body will look to break down the muscle AA’s for energy, although the body will look to utilize the AA’s in the blood before breaking down the muscle tissue. That is why it is good practice to train after the 12-16 hour fast and to consume a casein protein shake (this will be explained more in the protein shake section).
Intermittent Fasting and Exercise
Intermittent fasting and high-intensity resistance training can cause blood glucose to lower. This activates the release of the hormones adrenaline and nor-adrenaline which sets in motion the release of the hormones sensitive lipase (HSL). HSL aids the conversion of fats from fat cells to free fatty acids. These free fatty acids are then transported to the muscles/liver to be used as energy. In simple terms when the blood glucose is low, carnitine is increased and fat is burned as the primary fuel. The question is what is carnitine?
Carnitine is made in the body from the amino acids lysine and methionine. It plays a vital role in fat metabolism and 98% of carnitine is stored in the skeletal muscle. L-carnitine is an essential amino acid and is needed for long-chain fatty acid transportation, skeletal muscle contraction, regulation of protein balance and helps to use triglycerides as its primary fuel source.
Although health and athletic benefits of carnitine were unsubstantiated, a study in the Journal of Physiology states the following advantages:
- Improved quality of life by increasing fat loss and giving more energy.
- Increased athletic performance by speeding up the recovery from intense exercise, prevented oxidative stress on the CV system.
- Increased fat transport to cells, fat burning efficiency, and energy.
- Decreased visceral fat by increasing triglyceride and LDL cholesterol burning.
- In terms of athletic performance, 2 grams per day produced a decrease in R.P.E and an increase in performance at 50% and 80% VO2 max over a 30 minute period.
- Improved work capacity due to a decrease in pain, muscle damage and lactate acid production.
- Quicker recovery time from exercise due to less pain with more energy and a quicker depletion of lactate acid.
- May boost testosterone.
Researchers at the University of Virginia found an increase in the human growth hormone (HGH) after a 12 hour period of fasting. HGH preserves lean body mass and this is essential for keeping the body’s metabolism high. The lean mass has a higher energy requirement than fat mass. HGH also aids in the release of stored fat for energy and enhances cellular repair. Increased HGH level delays the onset of cortisol; which is a hormone used in the storage of belly fat.
Some research has indicated that body compositional changes are most noticeable due to the reduction in % of body fat. However, if you are eating enough calories to sustain your high-intensity resistance training (increasing training volume and reps to accommodate muscle growth) with adequate protein then the muscle will grow. Eating enough calories for body maintenance and muscle growth is two different concepts if you are feeling weak while training maybe you should consume more calories. Use the food diary to monitor your food intake; it is a great reflective tool!
Different IF Models
With most intermittent fasting protocols that extend the normal overnight fast, determining specific times to suit a certain lifestyle and needs whether it is 16, 24 or 36 hours needs to be understood. In terms of the feeding times, narrow the window of opportunity to 4, 8 or at the big end; 12 hours. This section will discuss common IF models used, and personal preferences it can be taken from what is wanted from this section and plan, and the results can be further implemented and evaluated depending on the approach.
The Lean Grains model of IF is the most common one used. It incorporates a 16 hour fast combined with an 8 hour eating period. It doesn’t matter when an 8 hour eating period starts (e.g. it can start at 9 am and finish at 5 pm or start at 1 pm and finish at 9 pm).
Breakfast can be skipped and lunch eaten, do whatever works personally, as long as the 16-hour fast protocol is followed. Due to the fact that the 16/8 model is undertaken every day, it should get one into good eating habits quite rapidly as many people eat when the clock tells them and not when they feel hungry. This system is about controlling the times that one can’t eat in relation to when one can. This is a great protocol for losing weight, getting control of appetite and eating within the right timeframe.
One the main issue with this 16/8 protocol is that skipping main meals throughout the day can reduce calorie intake. A solution to this overall reduction in weekly calorie intake is to eat big meals on a consistent basis. This is a good method for losing weight; however, the jury is out whether this protocol is the way forward for preserving lean body mass and increasing muscle gain.
Weekly Fasting Model
One of the best strategies to begin intermittent fasting is to do it once a week.
The above example shows that Monday is the last meal and your fast lasts until Tuesday, 24 hours later. The occasional fast has many health benefits such as weight maintenance, lowering LDLs and triglycerides within the blood, which is all good news for general heart health. As mentioned earlier, it is probably to maintain and not lose any weight due to the fact that one is not only missing out on 2 or 3 meals per week. This is actually a good approach to bulking up and detoxing the body at the same time. However, if one did want to lose weight one could add an additional day in the week. Many individuals add this day for this specific reason- to burn off the fat and to have a total weekly detox.
Many individuals drink distilled or mineral water not only to detox the body but also to suppress the appetite. During the 24 hours of fasting, the body will be in an alkaline state due to the intake of water. When the blood is in a state of acidosis from processed foods, pollutants, additives, and a generally poor diet, then there is a strong correlation between this and some lifestyle diseases (e.g. high blood pressure, CHD, etc). By having some time out with a 24-hour detox fast the blood pH returns back to an alkaline state. In addition to this, by successfully completing this 24 hour fast, it will prove that one can survive a fast without starving or dying.
Alternative Day Model
Alternative day fasting incorporates longer fasting periods by alternating days throughout the 7 days. With this plan, simply eating every other day (e.g. in the graph above dinner is eaten on a Monday night and then the body will not consume any food until Tuesday evening. Wednesday, one will eat all day and then start the 24-hour fasting/fed cycle again after dinner). This follows a 20-hour fasting and a 4-hours eating opportunity although the hours can be adjusted within the fast to suit certain needs as long as the fast is over 16 hours for optimal benefit.
A problem with this method of IF is that the body is in a fasting state for 20 hours, which is difficult to incorporate into a training routine. This method definitely takes a lot of detailed planning because there is only a 4-hour window of opportunity to eat, so a large meal needs to be prepared with adequate calories to sustain a healthy lifestyle. Some people work on the 600 calories per meal guideline when trying to lose weight, as this specific protocol the calories are obviously decreased due to the reduction in meals being consumed. The foods of choice should be high in protein and low GI, within the 600 calorie allowance.
Many health professionals believe that the longer that one fasts (not over 36 hours) the more health benefits and disease prevention will be evident. However, longer fasts may harm muscle health and general athletic performance. Gaining and preserving lean body mass is a critical element of living good, and if one is fasting for too long then there is a reduction in nutrient intake, fewer vitamins and minerals and other additional supplements (e.g. protein shakes).
That is why bodybuilders tend to use shorter fasts in the range of 16 hours – 20 hours per day that end in a workout and supplements and then is followed by eating ( 4- 8 hours). There is speculation that muscle mass is gained in the shorter fasts due to:
The fasted work out can stimulate a physiological state similar to an extended fast.
Eating the majority of your nutrients post-exercise can aid muscle growth and repair due to amino acid absorption (when a protein shake or high protein/low GI meal is eaten or both).
Other IF strategies are:
- Random Meal Skipping – this method of calorie cycling is flexible and any meal of choice can be skipped.
- Eat Stop Eat – where fasting occurs for 24 hours, twice a week maximum, followed by eating sensibly throughout the week (e.g. high protein, low GI) with cutting out the processed sugary junk foods.
- Warrior Diet – is eating 1 hour per day and fasting for 23 hours. This is a short term diet and would be hard to maintain an active lifestyle.
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