Flickr/TheCulinaryGreek

First we need to understand how our body uses fuel. There are 3 types of ‘macronutrients’ which provide our bodies with energy - carbohydrate, protein and fats (note: alcohol also yields energy but will not be included here as it is not essential to your body’s functioning as the other macronutrients are). Carbohydrates and protein provide us with about 17kJ per gram while fats provide us with about 37kJ per gram. In order to lose weight you need to consume fewer kilojoules than you are burning, no matter where these calories are coming from. For a 1kg fat loss per week, you need to burn an extra 5000kJ per day (or consume 5000kJ less per day).

Ordinarily, your body will use a mix of carbohydrate and fat stores for energy. Carbohydrates are your body’s preferred fuel, especially for your brain and your muscles. When your carbohydrate stores are running low and are not being topped up by your diet, your body will begin to use stored fat to fuel everyday processes and activity in a process called ketosis.

The Pros of Going Low Carb:

• Low carbohydrate diets usually result in rapid weight loss due to the way in which water is stored alongside carbohydrate stores
• Weight loss over a one-year period is comparable to a traditional low-fat diet
• Allowed foods include great tasting, high fat foods such as butter, cream, mayonnaise, cheese, steaks, etc
• Some studies show an improvement in blood glucose control and insulin sensitivity
• Some studies show an improvement in blood triglycerides levels and cholesterol levels, but ONLY when saturated fat is also restricted
• Ketosis suppresses appetite
• Protein can help keep you feeling fuller for longer

The Cons of Going Low Carb:

• Carbohydrates are found in many different types of foods including breads and cereal, fruits and some vegetables and some dairy foods. Avoiding these food groups in order to reduce the total amount of carbohydrate will result in a sub-optimal intake of the vitamins and minerals found in these foods
• Muscle loss is also common on low carb diets as the body looks to use protein for fuel. Since your heart is a muscle, this can result in heart rhythm disturbances. It can also lead to reduced exercise tolerance (from reduced glycogen stores in your muscle) as well as a slower metabolic rate long-term
• Low carbohydrate diets are also generally low in fibre and antioxidants which can increase your risk of certain cancers, especially bowel cancer
• Many studies show that reducing carbs in your diet results in a higher intake of fat (known as the carbohydrate-fat seesaw), which can be detrimental to the health of your cardiovascular system and liver
• Low carbohydrate diets that advocate high protein can cause damage to your kidneys and bones
• Having ‘allowed’ and ‘not allowed’ foods can result in disordered eating and may lead to weight re-bound in the long term when the person ‘goes off’ the diet
• Initial weight loss may be deceptive as it is usually water-loss from depletion of glycogen stores
• A lack of dietary carbohydrate can affect your mood and concentration

Conclusion:

At the end of the day it all comes down to controlling the total amount of calories that you are consuming, whether these come from carbs, fats or protein (or alcohol) (you can use the SpringDay food diary to help you track the amount of calories you are consuming). An ‘all-or-nothing’ approach tends to be difficult to maintain long-term. Using controlled portions of carbs and fats and proteins is the best way to ensure that you are not consuming too many calories, whilst still allowing you to have a balanced diet. For most people this usually means moderately reducing carbohydrates because most of us are out of touch with the amount of carbohydrate that constitutes a portion. As a general rule of thumb, a portion of carbohydrate-rich foods (pasta, rice, bread, etc) is about the size of your fist (cooked).

Also ensuring that you choose foods that have a lower energy density is essential. That is: foods that contain lots of vitamins and minerals without being too high in calories. This generally means choosing foods that are lower in fats and sugars and less processed foods. For carbohydrate foods, this would include wholegrain breads and cereals, beans and legumes, fruits and vegetables and unsweetened, low fat dairy products. These will fill you up without adding extra unwanted kilojoules to help you achieve healthy long-term weight loss.