Many people want to lose body fat: the rates of obesity in the English-speaking world is approximately 1/3 and another 1/3 are overweight. This means that individuals with a healthy bodyweight are only 1/3 of the population and are in a definite minority. The reduction of body fat is also one of the most common things that individuals want to achieve but diet success rates have been estimated to be around 5-10% in the long-term.
This shows that there is clearly need for a proper education in the way that the body uses and stores food, as well as how to structure a healthy diet that leads to weight loss and improved health. This article will provide the basics for those who are unsure: by the end of this article, you will understand the basics of how diet and nutrition work and which choices will allow you to lose bodyfat and improve your dietary health.
Diet is 90% of losing weight: whilst training and exercise in general can improve the way that we lose weight, this will not achieve anything if the diet is not already structured to allow us to lose weight. The saying that “abs are made in the kitchen” contains a kernel of truth: we cannot out-train a bad diet and it would be silly to try.
Calories are incredibly misunderstood. Whilst many people believe that food “contains” calories and they are to be avoided, the fact is that calories are simply a measure of energy and avoiding calories means avoiding food. Under-eating is as much of a nutritional problem as over-eating and calories should be understood as the basis for all goal-oriented dieting. The number of calories that the body uses in a day is called the total daily energy expenditure (TDEE) and there are various online calculators that can provide an initial estimate.
When we have figured out the number of calories that we use in a day, it is essential to eat less than this in order to lose fat. This is called a caloric surplus because we are consuming less calories than we are using, forcing the body to cover this short-fall using the energy stored in body fat. The weight loss equation, then, is this simple:
Calories consumed – calories used = weight change
When we eat less than we use, we lose weight and when we eat more than we use, we gain weight (either as muscle or as fat). This is 100% of the equation and there is no conceivable way for a health individual to eat less calories than they use and not lose weight! 
Whilst calories will determine whether or not we lose weight, we can improve the quality and speed of this process by manipulating the macronutrients in our diet. The macronutrients are carbohydrates, protein and fat. Protein is unquestionably the most important of these nutrients for those looking to lose body fat: a high protein intake is associated with increased muscle mass, increased fat loss and a preference to burn fat rather than muscle when we are at a caloric surplus . A high protein diet is considered to be anything from .5g per lb of bodyweight or more. The best protein sources are generally fatty fish (such as salmon), chicken, turkey, high-quality beef, high-quality eggs and protein powders, though this style of supplement should be considered only when struggling to consume enough protein in the form of whole foods.
There have been many debates about the effects of carbohydrates vs fats as the best nutrients for weight loss. We think this is silly (and the science agrees): there are almost no significant differences between carbs and fats for weight loss in large populations. The best approach is to improve the quality of both of these: low-quality foods, whether they are carbs (such as sugary drinks) or fats (such as hot dogs), will have a negative effect on the diet and health. Carbohydrates should be starchy and/or fibrous, whereas fats should be polyunsaturated and consumed in reasonable portions at once. The style of training that we perform is the biggest determinant in the balance of carbohydrates to fats: the more endurance training that we perform, the more carbohydrates we should consume .
3. Micronutrients and Supplementation
Micronutrients are the nutrients most commonly associated with health and wellness: vitamins, minerals and phytonutrients. These are best consumed through a wide variety of high-quality animal proteins, vegetables and other plant foods such as legumes and certain fruits. Micronutrients are essential in the maintenance of bodily functions from bone and muscle health to metabolism to immune function.
The main impact that micronutrients have on metabolism is through deficiency; failure to consume a sufficient quantity of certain vitamins and minerals is associated with a metabolic dysfunction. There are very few benefits to “mega-dosing” vitamins and minerals, but without a sufficient quantity, we will have sub-optimal metabolic function. The main vitamins associated with proper metabolic function are: B vitamins (especially B1, 2, 3, 6 and 12), Vitamin C and folate. The key minerals are Calcium, phosphorous, magnesium, iron, manganese and zinc.
Some of these compounds are difficult to achieve through a diet and may require supplementation as well as proper diet. For example, B12 is an incredibly difficult vitamin to find in bioavailable form – especially for those on a plant-based diet. For most individuals, this will require supplementation. The same is true of iron for those who are either plant-based, eat very little red meat or are women who have not begun menopause. These populations will likely need to supplement iron to improve the health of blood and muscular fluids, as well as proper energy balance.
When we are focusing on losing weight, training plays an important role in determining the speed of the weight loss and what we lose. Training can increase the amount of fat we lose, whilst reducing losses in muscle and other lean tissues. Training through a diet will also improve the hormonal balance and brain chemistry, which might otherwise suffer during a caloric deficit.
1. Resistance Training: Why is it Important for Losing Fat?
Resistance training is a great way to increase the amount of muscle mass that our body carries and increase the resting metabolic rate of the body. Additionally, when we add weight training to the regimen of an individual on a diet, it becomes possible to rapidly decrease body fat and increase muscle mass at the same time. This will mean a decreased body fat, an increase in lean mass and the preferential use of proteins for muscle repair and recovery.
The effects of resistance training are also subacute: whilst cardiovascular exercise requires the use of calories during exercise, the caloric demands of resistance training last up to 48 hours. During this time, the recovery of muscle proteins is the major caloric demand and can have comparable effects to cardiovascular exercise. However, the body’s hormonal response to resistance training is also more conducive to fat loss: when we rest after a training session, the body secretes greater amounts of hormones such as testosterone which are associated with a reduced capacity for holding bodyfat and an increased capacity for building muscle .
2. Aerobic Training: Structure and Use
Aerobic training covers a wide variety of exercises from jogging to circuits, intervals and CrossFit-style approaches. What these all have in common is a focus on increasing the amount of movement in the shortest possible time in order to task the cardiovascular system and muscular endurance. This includes the classic “cardio” approaches like running, rowing and cycling.
The idea behind performing aerobic training for weight loss is to increase the number of calories used in a day and thereby increase the severity of our caloric surplus. This means that aerobic workouts should focus on burning calories, increasing the duration and speed of movement and increasingly challenging movements. The harder we work, and the longer we work for, the more calories we are likely to burn.
HIIT is the best form of aerobic exercise and stands for high-intensity interval training. This means alternating between high-intensity exercise and low-intensity exercise. For example, jogging for a minute followed by 30s of sprinting. This form of exercise allows us to develop endurance at both low speeds and high speeds whilst burning a maximal amount of calories and increasing important aerobic performance markers such as VO2 max to a greater extent than either high- or low-intensity exercise alone . This should be performed after resistance training but prior to lower-intensity aerobic exercise.
Low-Intensity Steady State (LISS) exercise focuses on a much lower workload extended out over a much greater space of time. This is the kind of exercise that was revered as the best way to lose weight prior to the turn of the 21st century and has only recently taken a backseat to more intense styles of training. This includes the kind of cardio exemplified by spending an hour on a treadmill: long, low intensity work dedicated to breaking a sweat and covering miles and miles on foot or by cycle. This still has its place in a well-conceived training program for fat loss, but this is best used as an accompaniment to HIIT and performed at reasonable intensities. The goal with this form of exercise should be to sustain a given intensity (such as a challenging km/h) for as long as possible, rather than simply enduring for as long as possible.
Losing Fat – Don’t Forget These
Sleep is an essential process for the proper regulation of bodily processes and this includes metabolism and the hormonal processes governing it. The failure to achieve proper sleep quality and quantity has been shown to result in the suppression of testosterone and increases in cortisol secretion, associated with stress and poor mood . Chronic elevation of this hormone can result in the body fat being incredibly stubborn.
Proper sleep has been shown to be around 8-9 hours as an absolute minimum for proper biological functioning. Anything below this will negatively impact all the markers of weight loss, as well as healthy brain function and athletic performance. This should also be high-quality sleep – this is to say that it is sleep in a dark, cool room without being hungry or bloated, neither dehydrated nor full, and without excessive stress and anxiety.
Water is a necessary substance for the proper regulation of homeostasis in general and the metabolism more specifically. Without a proper intake of fluids, we will experience an excessive secretion of cortisol which inhibits fat loss. Additionally, water is necessary for the hydrolysis of fat tissues, which is often the starting point for burning fat. If we do not have a sufficient water intake or are experiencing dehydration, this process cannot occur efficiently and fat loss will be sub-optimal.
The process of losing fat is actually far simpler than most people think. For the sake of simply losing weight, calories are by far the most important variable. If we are at a calorie deficit – regardless of what foods we are eating – we will lose body fat. The quality, speed and performance changes associated with this weight loss will be determined by macronutrients, micronutrients, sleep quality/quantity and maintaining proper hydration. Losing fat can be broken down into a single sentence: ‘using a variety of high-quality foods, eat less calories than you use – move, drink and sleep a lot’.
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 Leproult and Van Cauter (2011): ‘Effect of 1 week of sleep restriction on testosterone levels in young healthy men’. Journal of the American medical association, 305(21), pp.2173-2174