Body mass reductions are driven by a negative energy balance.
A negative energy balance is a state where the amount of energy coming into the
body is less than the amount of energy going out of the body; creating an energy deficit. This energy deficit is the driver of body mass loss, as internal stores/reserves of energy provide the energy required to complete ‘energy out’ tasks, thus body mass is lost. A negative energy balance can be created by reducing energy intake from food and drink. Or by increasing energy expenditure by moving more, or a combination of the two.
Obviously the negative energy balance results in a reduction in whole body mass. There are not many occasions where a person’s aim is to reduce whole body mass, including both fat mass and lean muscle mass. Especially not from a health or athletic perspective, where lean muscle mass is strongly associated with improved health, reduced risk of disease and greater athletic prowess.
Note that a large negative energy balance can impair key hormonal functions, and thus have a significant effect on metabolic rate. This is a key factor to consider when creating a weight loss programme, small negative energy balances should be utilised initially in order to prevent such impairment occurring, this will also allow for the maintenance of lean mass which will support maintenance of metabolic rate.
Realistically when dieting for fat loss the aim is to reduce body fat while maintaining lean mass. This is extremely difficult since a negative energy balance causes overall body mass loss to occur and directing that reduction in body mass to favour reductions in fat mass as opposed to lean mass takes significant skill and nutritional know how. This is ultimately achieved through the manipulation of macronutrients and implementation of a structured exercise regime.
Protein requirements when dieting.
When dieting, muscle mass loss is always an issue. When calories are reduced the body retains less protein so more is required. Methods of maintaining muscle mass during weight or fat loss have been an area of interest within the academic research for many years.
In overweight, non-training individuals, a protein intake of 1.5 g/kg maybe required to reduce losses in lean body mass during a caloric deficit. More recent research has indicated that protein intakes 3 times the RDA (2.4 g/kg or 2.3 – 3.1 g/kg of fat free mass) may protect fat-free mass during short-term weight loss.
Consuming sufficient, or elevated protein intakes, when dieting also offers additional benefits as protein is the most satiating macronutrient, thus increasing the feelings of fullness and satisfaction. Protein may also increase caloric expenditure via thermogenesis and help to maintain stable blood glucose concentrations. Protein intake at the higher end of the spectrum also appears to limit weight regain following a diet.
With the knowledge that successful weight loss requires sustained satiety, despite a negative energy balance, and sustained basal energy expenditure, despite body weight losses, while sparing lean mass it is generally accepted that when dieting protein intakes of around 3 g/kg would be optimal for maintaining lean muscle mass.
Carbohydrate and fat intake when dieting
The common trend at present is to reduce, or completely eliminate carbohydrates from the diet and replace it with fat. High fat, low carb diets such as the Atkins diet have grown in popularity as peoples’ fear of carbohydrates grows.
In truth carbohydrates are not fattening as long as they are consumed within your individual calorie and carbohydrate requirements. Large quantities of carbohydrates that contribute to a sustained positive energy balance will drive fat mass gain. But then large quantities of protein or fat will also drive fat mass gain if they contribute to a positive energy balance.
That said, don’t fear carbohydrates, and don’t eliminate them entirely. Just focus on consuming the less energy dense carbohydrates such as dark green leafy vegetables and thin-skinned fruits such as berries, apples and pears. This will allow you to reap the numerous health benefits of the nutrient and fibre dense carbohydrates but without consuming excessive calories, managing the negative energy balance.
The more energy dense starchy carbohydrates such as potatoes, rice, pasta, oats and bread should be consumed sparingly, as they contain more calories. Generally speaking consuming them around exercise, either before, after or both, will benefit exercise performance, resulting in greater work capacity, greater energy expenditure and greater adaptation, all of benefit to fat loss.
Just as you should not fear carbohydrates, you should not also fear fat when aiming to reduce fat mass. Research has shown that trans fats are likely to be the only fats that pose any real harm to your health, beyond that consuming a mix of the other fat sources (saturated, monounsaturated and polyunsaturated fat) will be of benefit.
The one issue with fat, however, is that fat is the most calorific macronutrient. Fat provides 9 kcal/g, compared to protein and carbohydrates which both provide 4 kcal/g. Fat is also the least satiating macronutrient, so it does not fill you up but while having the most satisfying taste. As you can see, this is almost developing into a recipe for disaster: it’s the most energy dense, it tastes good and it does not fill you up. In that regards, caution is required not to over consume fat. Opting for the lower or reduced fat options and lean meats is likely going to benefit your ability to sustain a negative energy balance. But be wary that low fat does not necessarily mean low calorie, so read the food labels to confirm.
Fat loss supplements
In truth, there are very few, if any, legal supplements in existence that can directly result in fat loss. Despite the marketing hype surrounding fat burners, diet pills, and nutritional juices.
As discussed previously, a negative energy balance will result in body mass loss, and a slight manipulation to the macronutrient split will favourably drive that deficit toward the reduction of fat mass while maintaining lean mass. There are a few supplements that can indirectly influence fat loss: Acetyl-L-Carnitine, Omega 3 – Fish Oils, Vitamin D3 and a high quality protein source (such as Probiotic Whey).
Focus on the basics: create a negative energy balance by eating lower calorie foods and reducing portion sizes, while also exercising more; increase your protein intake slightly, perhaps through supplementing Probiotic Whey enabling you to maintain muscle mass; focus on low calorie fruits and vegetables and be sparing with your starchy carbohydrates and fats; stay hydrated and supplement simply with omega-3, vitamin D and whey protein.
Article by Matt Jones, MSc Nutrition