Despite the $255 billion global diet industry, £2 billion in the UK, objective studies show broad agreement that diets don’t work. “I would agree with that,” says Trine Balsvik, “Eating less, focussing only on calories, it’s the worst, depressing, infuriating. Totally miserable. That’s not a life.”
Trine Balsvik lives in a small village called Hell in the middle of Norway with her partner and one of her two grown-up daughters. Now 45, she says, “I have tried many weight loss diets with no success.”
Balsvik weighed 80 kilos when she read about a new study that was recruiting subjects for a seven-week trial combining time-restricted eating (TRE) and high intensity interval training (HIIT), “I like contributing to scientific research, but this one really attracted me. I wanted to lose weight.”
The seven-week randomised controlled trial split 131 overweight or obese reproductive-aged women with an average age of 36 and split them into four groups. One doing TRE alone, restricting their energy intake to no greater than a 10-hour daytime ‘eating window’, starting no later than 9am, the second doing HIIT consisting of supervised treadmill running sessions three times a week, a third doing a combination of TRE and HIIT and a control group that did nothing.
Other than time restrictions, the participants were asked to eat and drink as they would normally. Participants were advised to open their eating window no later than 10am.
A collaboration between Norwegian and Australian authors, the study, which was published in Cell Metabolism last October, saw improvements in a number of crucial biomarkers in all the groups except the control, including a wide improvement in blood sugar reactions and a reduction in visceral ‘belly fat’ that indicates a raised risk of cardio metabolic disorders like heart disease and Type 2 diabetes.
Balsvik was part of the TREHIIT group, which, unsurprisingly, did best. Balsvik lost half a stone (three kilos) in seven weeks, her BMI dropped from 29.5 to 28.5 and she lost nearly 10% of visceral ‘belly’ fat, which was pretty average within her group.
She says the hardest thing about the study was the 30 minutes of travel to the exercise sessions and the impact running had on her hips and knees. Other than that she says it was “easy”.
And here is where this small study is interesting. Easy? The word is rarely seen in the same sentence as ‘diet’. While the HIIT was a successful intervention, Balsvik has not kept it up since the study ended two years ago, but she still has enthusiasm for TRE, which she found effortless.
“I was very anxious before I started. Wondering ‘How am I going to do my work if I haven’t eaten anything?’ For two or so days I had this sense of hunger but not extreme and then my body liked the routine, I had more energy and was in a great mood. It was the complete opposite to what I expected.”
After the study she continued following TRE, losing a further 9lbs (4kg) and a further 10% of visceral fat (belly fat around organs in the abdominal cavity). “I stick to it. Sometimes we eat a bit later in the evening at the weekend and my body reacts and I feel sick, like something is wrong with me. My boyfriend has joined me on it now.” He has not seen significant improvements, “I think his eating window is too long, at 13 hours, and too late.”
One of the study’s authors, Kamilla Haganes of the Department of Circulation and Medical Imaging at the Norwegian University of Science and Technology, says TRE should not be confused with Intermittent Fasting because it is a “chrono nutritional strategy”.
Popular fasting regimes such as 16:8, 5:2 or OMAD (one meal a day) “are mainly linked to the energy restriction achieved with intermittent periods of fasting. In contrast, TRE primarily emphasises shifting energy intake to parts of the day where the human body is physiologically prepared to digest and utilise energy.”
How TRE works
TRE works in harmony with our circadian rhythms, the body, brain and even individual cells and genes having their own clocks that work roughly in synch with the 24-hour day. Food and light switch certain functions on. Sleep, body temperature, hormone levels and digestion are all affected by these natural fairly inflexible circadian rhythms across all human beings.
One very famous study reverted a number of self-identifying “night owl” students to natural “larks” over a matter of a few days simply by taking away all artificial light sources at night.
Another study found that even if there is no weight loss, TRE still improves metabolic markers in prediabetic men. Balsvik is now effortlessly over a stone lighter two years on, with a BMI of 27, and greatly reduced visceral fat, having cut down on ultra processed foods and increased protein and vegetables out of choice.
She plans to resurrect the HIIT regime with exercise that’s easier on her knees. The exercise will help, she says, but “Unless you are a naturally motivated person, you need encouragement…” A sentiment many of us will understand.
One study last summer found TRE most effective implemented between seven am and three pm. Another found that those who stick to TRE but eat a later dinner see less benefits.
So, eat your evening meal early. Your body will thank you.