New data published in South African showed that two in three SA women are overweight or obese and only one in three are at a healthy weight. But throw the word “diet” into conversation and this will trigger an avalanche of debate among friends. There are so many popular diets that seem to contradict each other and this can create much confusion as to which is the most effective for weight loss.
Let’s look at four popular diets for weight loss.
Low carbohydrate diets
In one of the most heated debates in nutrition history the low carbohydrate/ high fat has become popular in the diets of many South Africans. Despite all the media attention, a local review led by Dr Celeste Naude from the Centre for Evidence-based Healthcare in Stellenbosch combined the findings of 19 clinical trials on more than 3 000 participants to show that low carbohydrate diets are not more effective for weight loss in comparison to a kilojoule-reduce yet balanced diet. In addition, little difference was detected in heart disease and diabetes risk amount the two types of diets.
“Everything from lentils to lollipops contains carbohydrates,” notes Dr David Katz, a prominent nutrition researcher. Treating the expanse of foods containing carbohydrates as one all-inclusive food group is short-sighted as all plant-based foods (fruit, vegetable, nuts, seeds, and legumes wholegrains) are a source of carbohydrates. We know that the new modern diets are high in refined carbohydrates and simple sugars, both of which are carbohydrates. However, a diet containing some carbohydrates is essential for fiber and nutrients. Focus should be less on refined sugary carbs and more on high fiber, slow release carbohydrates such as fruit, starchy vegetables, and legumes.
The Palaeolithic (Paleo) diet mimics the eating style of our ancestors: lean meat and fish, nuts, and lots of fruits and vegetables. Processed foods (including sugar and salt), dairy, legumes, and grains are excluded.
There is a scientific case for the Paleo diet, based in part on anthropological studies showing low rates of chronic disease and obesity in our Paleo ancestors. A review in the British Journal of Nutrition suggests that a protein-rich meal sends feedback signals of fullness to the brain. This can be advantageous in weight loss diets. It is important to remember that this diet’s support of protein must not be misinterpreted as licence to eat large amounts of protein from processed meats such as viennas, polony and cold meats, while overlooking that the diet reinforces large intakes of fruit and vegetables.
Low fat diet
The low fat diet from the 1990’s suggested that low intakes of fat are ideal for weight loss. Research on this diet showed good health benefits and weight loss when a diet is low in fat. However, critics of the low fat diets relate came with a concurrent increase in rates of obesity. It is interesting to note though that a lot of research has showed that people are no necessarily eating less fat but rather we are overall eating too much kilojoules from all foods.
It is important to remember that not all fats are created equal. Intentionally limiting good monounsaturated fats like nuts, seeds, avocados, and olive oil can actually negatively influence health. Since all fats have higher kilojoule content (compared to carbohydrates or protein) one-way to control total kilojoules for weight loss sis to pay attention to your fat intake. Favour plant-based fats such as olives, avocado, nuts and seeds should be over animal fats like fat on meat, chicken skin, and full cream dairy. Interestingly, coconut oil is also a saturated fat.
The Mediterranean diet is generally well liked by dieters. Mimicking traditional dietary patterns of Mediterranean countries, this diet encourages olive oil, fish and seafood, fruits, vegetables, legumes, nuts and seeds, moderate intakes of red wine and low fat dairy, and limited red meat.
Scientific support for Mediterranean eating is very strong. Rich in omega-3s and generous consumption of fibre, nutrients and antioxidants, this dietary pattern is associated with vitality and longevity and reduced cancer risk. The Mediterranean diet also significantly supports weight loss. Large intervention trials such as the Lyon Diet Heart Study and PREDIMED (Effects of the Mediterranean Diet on the Primary Prevention of Cardiovascular Diseases) have also shown impressive heart benefits. Use of olive oil as dressings in salads, vegetables and legume dishes for a heart-healthy, weight loss boost.
The standout nutritional factor in this diet is the quality of fat, favouring monounsaturated fats in olive oil over cholesterol raising saturated and trans fats in red meat and processed foods. However, as mentioned above, regardless of the type of fat, gram for gram, these fats have the same calorie content and this does not justify excessive intake of fat
If we look at all the evidence of the best parts of any diet, a healthy diet is one where kilojoules eaten are less than what is needed, with minimal processed and highly refined foods that does not compromise eating nutrient-rich foods. As nutritionist Michael Pollen so aptly puts it, “Food, not too much, mostly from plants.
- Buckland G, Bach A, Serra-Mjem LS. Obesity and the Mediterranean diet: a systematic review of observational and intervention studies. Obesity Reviews. 2008; 9: 582-593.
- Dietitians of Canada. The popular Paleo diet. PEN; November 2014.
- Katz DL and Meller S. Can we say which diet is best for health? Annual review of public health, 2014; 35: 83-103
- Naude CE et al. Low Carbohydrate versus Isoenergetic Balanced Diets for Reducing Weight and Cardiovascular Risk: A Systematic Review and Meta-Analysis. PLOS ONE. 2014; 9 (7): 1-30.
- Trichopoulou A et al. Definitions and potential health benefits of the Mediterranean diet: views from experts around the world. BMC Medicine; 2014: 12 (112).
- Westerterp-Plantenga MS, Lemmens SG, Westerterp KR. Dietary protein – its role in satiety, energetics, weight loss and health. British Journal of Nutrition, 2012; 108: S105–S112.