Fitness magazines, websites and the wider media place sugar consumption as one of the primary causes of weight gain, but what does the research tell us?

A 2013 systematic review and meta-analysis (1) on the subject found the following results:

In adult trials without strict control on overall food intake, reducing dietary sugar intake was associated with decreases in body weight. Likewise, increases in sugar intake was associated with increases in body weight. 

However, under isoenergetic conditions, replacing sugars with calorie equivalent macronutrients showed no change in body weight. 

So what does this mean?

In a non controlled environment, where calories are not being tracked, general advice to reduce sugar intake is beneficial for weight loss for the following reasons: 

> sugary food is readily available and an easy way to over consume energy

> sugar is not very filling, and so doesn’t prevent over consumption later in the day

> spikes and drops in blood sugar levels can often leave people feeling even hungrier, and more likely to continue consuming calories throughout the day

the above points are more likely to correlate with an overconsumption of energy, causing weight gain and preventing weight loss 


Sugar does not inherently cause weight gain. Overall energy balance dictates weight changes, whether this energy is coming from sugar or anywhere else. When calories are being monitored, including some sugar in a weight loss diet may be beneficial for the following reasons:

> Sustainability: removing entire food groups is rarely sustainable and not conducive with long term success

> Adherence: people tend to enjoy sugary foods. Even if a chocolate bar may not be quite as filling as a sweet potato, when adhering to a calorie deficit, the psychological benefit of occasionally being able to enjoy a snack you like and still achieve weight loss may outstrip the benefit of feeling slightly fuller. 

> Facts not Fads: the demonisation of sugar in the media is the latest fitness fad. Being caught up in the scare mongering can lead people to crazy conclusions such as cutting out fruits, diary or anything else, because of the “toxic sugar”. This can build longstanding issues with our perception of food.

The Take home

Eating less energy than you expend will result in weight loss. Completely removing sugar from your diet may help you achieve this, but if this energy is replaced with something else, it will not. Keeping sugar in your diet will not hinder your weight loss as long as a calorie deficit is maintained. However, high levels of sugar may give you a harder time feeling full and adhering to your deficit.

Consume responsibly in line with your goals. 



(1) Morenga et al, 2013. Dietary sugars and body weight