It is tempting to believe that that a magic pill or superfood can boost your metabolism, burn fat, and get you that perfect bikini body in time for summer. But do these things really exist?
Let’s take a look at six foods claiming to help with weight loss, and sort the fact from the fiction.
High protein diets have been linked with weight loss for a number of reasons. Firstly, protein is essential for protecting your muscle mass, and therefore, your metabolism. Secondly, it helps to regulate appetite and reduce overall caloric intake. Lastly, protein digestion increases your basal metabolic rate about 5-10% more than carbohydrates, and at least 15% more than dietary fats.
However, proteins and protein powders do not have the ability to ‘burn fat’, as often claimed. In fact, any excess calories from protein will be converted into glucose and stored, similarly to carbohydrates and dietary fats.
Research indicates that our bodies can’t use more than 20-30g of protein for muscle growth within a small timeframe, even after a workout. So, if you are having a protein shake in close proximity to a main meal, the extra protein and calories may be adding more to your waistline than your biceps.
So what’s the best way to use protein powder for weight loss? Use it at meal times when no wholefood protein sources are available, to help keep you full (i.e. in your breakfast smoothie). Or, straight after a workout to build muscle, if you are not planning to have a meal within the hour. Protein powders can also be used as a snack option between meals.
Made famous by Dr Oz in 2012, Garcinia Cambigia is a plant based extract that contains an active ingredient called hydroxycitric acid (HCA). It claims to inhibit fatty acid and cholesterol production, and boost metabolism, with some positive results in animal studies. However, the evidence is lacking for humans, with no trials to date demonstrating significant weight loss or cholesterol-lowering effects over 12 weeks.
Green tea is often found on superfood lists, and for good reason. Epidemiological studies have demonstrated that higher intakes of green tea are protective against certain chronic diseases. For example, it is a good source of catechin polyphenols, shown in human studies to reduce the risk of heart disease and cancer.
But does it boost your metabolism and aid with weight loss? Studies have shown that two compounds in green tea – caffeine and Epigallocatechin gallate (EGCG) – may work in synergy to increase metabolism and break down body fat, at a very modest level. At best, green tea may increase your metabolism by 3-4%, if consuming more than four cups of tea per day. But many studies show no weight loss benefit. As we know – everyone is different!
Similarly to green tea, caffeine is the active ingredient linking green coffee bean extract (GCE) and guarana to weight loss. Human studies have shown that caffeine may increase metabolism by 3-10% in doses of approximately 200mg per day (7).
GCE and guarana are available to purchase in pure supplement form, however they are most commonly found added to sports supplements, including pre-workout protein bars and shakes, and energy drinks. The amount of ingredients added to these products provides less than 200mg of caffeine per serve, or in other words, no better than a regular coffee. In such small doses, it may not achieve the desired effect. Not to mention, the calories in those products may override any metabolic benefit.
But GCE has another thing going for it. It contains chlorogenic acid, which studies have shown may reduce the absorption of sugars and fatty acid synthesis. Three key studies of GCE have demonstrated an average weight loss of 2-3kg across a total of 142 participants.
However, there are a few catches. The thermogenic effects of caffeine are short-lived, and can reduce after repeated exposure, as the body develops a tolerance. And, scientific reviewers express concern over the credibility and efficacy of the GCE results, as these studies were hosted by organisations standing to profit from a positive result.
There seems to be only one well-known study showing a weight loss benefit for apple cider vinegar, independent of other lifestyle choices. In this study, a group of obese males consuming one to two tablespoons of apple cider vinegar daily for 12 weeks dropped 1.2kg, as well as reducing their blood lipids and percentage body fat (8). However, there have been many studies before and after this one, showing no metabolic benefits at all.
Despite this, apple cider vinegar certainly has health benefits. For example, it can be added to a meal to reduce glycemic index and slow down gastric emptying. This outcome can, in turn, help to regulate insulin and blood sugar levels, increase satiety between meals, and maybe, reduce daily calorie intake.
The words chilli and weight loss have been paired frequently over the last 15 years. The active ingredient in chilli called capsaicin has been shown to boost metabolic rate and reduce appetite when consumed as part of a meal. However, like caffeine, the effects are short lived and seem to reduce over time as tolerance develops.
Overall, chilli has been linked to both positive and negative health outcomes. Some studies warn against excessive chilli intake, as it can cause inflammation and damage to the oesophagus and stomach lining.
Some of these foods may assist with fat burning and metabolism. However, the only reliable way to lose weight and achieve your best bikini body yet, without extreme intervention, is through old-school good nutrition and exercise!