Once inside the mitochondrion, the dominant way that the bound fatty acids are used as fuel in cells is through β-oxidation, which cleaves two carbons off of the acyl-CoA molecule in every cycle to form acetyl-CoA.[24] Acetyl-CoA enters the citric acid cycle, where it undergoes an aldol condensation with oxaloacetate to form citric acid; citric acid then enters the tricarboxylic acid cycle (TCA), which harvests a very high energy yield per carbon in the original fatty acid.[25][26]
Intermittent fasting is another way to achieve ketosis. This doesn’t suggest going days without food, but rather intermittent fasting. You can eat for eight hours and then fast for 16 hours, or eat a low-calorie diet for a few days (about 1,200 daily calories if you’re a woman and 1,500 daily calories if you’re a man). As you take in less food, your body uses more of its fat stores for fuel.
Under these circumstances, as soon as the body’s limited reserves of glucose starts to run out, your entire body switches its fuel supply to run almost completely on fat. The levels of the fat-storing hormone insulin levels become very low, and fat burning increases dramatically. You thus get easy access your fat stores, and can burn them off. This is great for losing excess weight. Studies prove that keto diets result in more weight loss, faster. There are also more potential benefits.
When you eat less than 50 grams of carbs a day, your body eventually runs out of fuel (blood sugar) it can use quickly. This typically takes 3 to 4 days. Then you’ll start to break down protein and fat for energy, which can make you lose weight. This is called ketosis. It's important to note that the ketogenic diet is a short term diet that's focussed on weight loss rather than the pursuit of health benefits. 
Lemons are also keto-friendly, so go ahead and add a spritz of lemon juice to your ice water. One typical lemon wedge has about 0.5  g of net carbohydrates and only 0.2 g of sugar. The fruit also offers  3.7 mg of vitamin C, which is 6.2 percent of the DV. Lemon water contains antioxidants that fight free radicals, and it also promotes healthy digestion, according to the Cleveland Clinic.